diff --git a/components/match/MatchLineupScoreDisplay.vue b/components/match/MatchLineupScoreDisplay.vue
index aaaf8da2..cbe67ae6 100644
--- a/components/match/MatchLineupScoreDisplay.vue
+++ b/components/match/MatchLineupScoreDisplay.vue
@@ -22,7 +22,7 @@
       </template>
     </span>
 
-    <small v-if="matchMap && halves">
+    <small v-if="matchMap && halves && hasSideWins">
       [<span class="text-yellow-500">{{ tWins }}</span
       >:<span class="text-blue-400">{{ ctWins }}</span
       >]
@@ -31,7 +31,7 @@
 </template>
 
 <script lang="ts">
-import { e_sides_enum } from "~/generated/zeus";
+import { matchSideWins } from "~/utilities/matchSideWins";
 
 export default {
   props: {
@@ -172,32 +172,18 @@ export default {
       return this.match.lineup_1_id === this.lineup.id;
     },
     sideWins() {
-      if (!this.matchMap?.rounds) {
+      if (!this.matchMap) {
         return { ct: 0, t: 0 };
       }
-      const chronological = [...this.matchMap.rounds].reverse();
-      let ct = 0;
-      let t = 0;
-      let prev1 = 0;
-      let prev2 = 0;
-      for (const round of chronological) {
-        const lineupWon = this.isLineup1
-          ? round.lineup_1_score > prev1
-          : round.lineup_2_score > prev2;
-        const lineupSide = this.isLineup1
-          ? round.lineup_1_side
-          : round.lineup_2_side;
-        if (lineupWon) {
-          if (lineupSide === e_sides_enum.CT) {
-            ct++;
-          } else if (lineupSide === e_sides_enum.TERRORIST) {
-            t++;
-          }
-        }
-        prev1 = round.lineup_1_score;
-        prev2 = round.lineup_2_score;
-      }
-      return { ct, t };
+      return matchSideWins(this.matchMap.rounds, this.isLineup1, {
+        currentSide: this.isLineup1
+          ? this.matchMap.lineup_1_side
+          : this.matchMap.lineup_2_side,
+        mr: this.match.options?.mr,
+      });
+    },
+    hasSideWins() {
+      return this.sideWins.ct + this.sideWins.t > 0;
     },
     ctWins() {
       return this.matchMap ? this.sideWins.ct : undefined;
diff --git a/tests/utilities/matchSideWins.spec.ts b/tests/utilities/matchSideWins.spec.ts
new file mode 100644
index 00000000..aeee3436
--- /dev/null
+++ b/tests/utilities/matchSideWins.spec.ts
@@ -0,0 +1,128 @@
+import { describe, expect, it } from "vitest";
+import {
+  matchSideWins,
+  normalizeSide,
+  oppositeSide,
+  sideForRoundNumber,
+} from "~/utilities/matchSideWins";
+
+describe("normalizeSide", () => {
+  it("treats T as TERRORIST", () => {
+    expect(normalizeSide("T")).toBe("TERRORIST");
+    expect(normalizeSide("TERRORIST")).toBe("TERRORIST");
+    expect(normalizeSide("CT")).toBe("CT");
+    expect(normalizeSide(null)).toBeNull();
+  });
+});
+
+describe("sideForRoundNumber", () => {
+  it("uses the current side for the whole first half", () => {
+    expect(sideForRoundNumber(4, "TERRORIST", 8, 12)).toBe("TERRORIST");
+  });
+
+  it("flips first-half sides once the map is past MR", () => {
+    expect(sideForRoundNumber(4, "CT", 16, 12)).toBe("TERRORIST");
+    expect(sideForRoundNumber(14, "CT", 16, 12)).toBe("CT");
+  });
+
+  it("swaps every three overtime rounds", () => {
+    expect(sideForRoundNumber(25, "CT", 26, 12)).toBe("CT");
+    expect(sideForRoundNumber(28, "CT", 28, 12)).toBe("TERRORIST");
+  });
+});
+
+describe("matchSideWins", () => {
+  it("returns zeros when there are no rounds", () => {
+    expect(matchSideWins([], true)).toEqual({ ct: 0, t: 0 });
+  });
+
+  it("counts from score deltas so a wrong winning_side cannot steal a round", () => {
+    const rounds = [
+      {
+        round: 1,
+        lineup_1_score: 1,
+        lineup_2_score: 0,
+        lineup_1_side: "TERRORIST",
+        winning_side: "CT",
+      },
+      {
+        round: 2,
+        lineup_1_score: 1,
+        lineup_2_score: 1,
+        lineup_1_side: "TERRORIST",
+        winning_side: "TERRORIST",
+      },
+    ];
+    expect(matchSideWins(rounds, true)).toEqual({ ct: 0, t: 1 });
+    expect(matchSideWins(rounds, false)).toEqual({ ct: 1, t: 0 });
+  });
+
+  it("accepts T as the terrorist side", () => {
+    const rounds = [
+      {
+        round: 1,
+        lineup_1_score: 1,
+        lineup_2_score: 0,
+        lineup_1_side: "T",
+        winning_side: "T",
+      },
+    ];
+    expect(matchSideWins(rounds, true)).toEqual({ ct: 0, t: 1 });
+  });
+
+  it("does not depend on the incoming round order", () => {
+    const rounds = [
+      {
+        round: 2,
+        lineup_1_score: 2,
+        lineup_2_score: 0,
+        lineup_1_side: "TERRORIST",
+      },
+      {
+        round: 1,
+        lineup_1_score: 1,
+        lineup_2_score: 0,
+        lineup_1_side: "TERRORIST",
+      },
+    ];
+    expect(matchSideWins(rounds, true)).toEqual({ ct: 0, t: 2 });
+  });
+
+  it("infers sides from the current map assignment when rounds omit them", () => {
+    const rounds = [
+      { round: 1, lineup_1_score: 1, lineup_2_score: 0 },
+      { round: 2, lineup_1_score: 2, lineup_2_score: 0 },
+      { round: 13, lineup_1_score: 3, lineup_2_score: 0 },
+    ];
+    expect(
+      matchSideWins(rounds, true, { currentSide: "CT", mr: 12 }),
+    ).toEqual({ ct: 1, t: 2 });
+  });
+
+  it("falls back to winning_side when scores never increment", () => {
+    const rounds = [
+      {
+        round: 1,
+        lineup_1_score: 0,
+        lineup_2_score: 0,
+        lineup_1_side: "TERRORIST",
+        winning_side: "TERRORIST",
+      },
+      {
+        round: 2,
+        lineup_1_score: 0,
+        lineup_2_score: 0,
+        lineup_1_side: "TERRORIST",
+        winning_side: "CT",
+      },
+    ];
+    expect(matchSideWins(rounds, true)).toEqual({ ct: 0, t: 1 });
+  });
+});
+
+describe("oppositeSide", () => {
+  it("swaps CT and T", () => {
+    expect(oppositeSide("CT")).toBe("TERRORIST");
+    expect(oppositeSide("TERRORIST")).toBe("CT");
+  });
+});
diff --git a/utilities/matchSideWins.ts b/utilities/matchSideWins.ts
new file mode 100644
index 00000000..83ed59d4
--- /dev/null
+++ b/utilities/matchSideWins.ts
@@ -0,0 +1,163 @@
+import { e_sides_enum } from "~/generated/zeus";
+
+export type Side = "CT" | "TERRORIST";
+
+export type SideWinRound = {
+  round?: number | null;
+  lineup_1_score?: number | null;
+  lineup_2_score?: number | null;
+  lineup_1_side?: string | null;
+  lineup_2_side?: string | null;
+  winning_side?: string | null;
+};
+
+export type SideWins = { ct: number; t: number };
+
+const EMPTY: SideWins = { ct: 0, t: 0 };
+
+export function normalizeSide(
+  value: string | null | undefined,
+): Side | null {
+  if (value === "CT" || value === e_sides_enum.CT) {
+    return "CT";
+  }
+  if (
+    value === "T" ||
+    value === "TERRORIST" ||
+    value === e_sides_enum.TERRORIST
+  ) {
+    return "TERRORIST";
+  }
+  return null;
+}
+
+export function oppositeSide(side: Side): Side {
+  return side === "CT" ? "TERRORIST" : "CT";
+}
+
+function scoreOf(value: number | null | undefined): number {
+  return typeof value === "number" && Number.isFinite(value) ? value : 0;
+}
+
+// Current map sides apply to the half being played now. First half is
+// rounds 1..mr; second half flips; CS2 overtime is 3-round halves starting
+// on the second-half assignment.
+export function sideForRoundNumber(
+  roundNumber: number,
+  currentSide: Side | null,
+  latestRound: number,
+  mr: number,
+): Side | null {
+  if (!currentSide || roundNumber <= 0 || mr <= 0) {
+    return null;
+  }
+
+  const firstHalfSide =
+    latestRound <= mr ? currentSide : oppositeSide(currentSide);
+
+  if (roundNumber <= mr) {
+    return firstHalfSide;
+  }
+  if (roundNumber <= mr * 2) {
+    return oppositeSide(firstHalfSide);
+  }
+
+  const otIndex = roundNumber - mr * 2;
+  const otHalf = Math.ceil(otIndex / 3);
+  const secondHalfSide = oppositeSide(firstHalfSide);
+  return otHalf % 2 === 1 ? secondHalfSide : firstHalfSide;
+}
+
+function lineupSideForRound(
+  round: SideWinRound,
+  isLineup1: boolean,
+  currentSide: Side | null,
+  latestRound: number,
+  mr: number,
+): Side | null {
+  const own = normalizeSide(
+    isLineup1 ? round.lineup_1_side : round.lineup_2_side,
+  );
+  if (own) {
+    return own;
+  }
+  const other = normalizeSide(
+    isLineup1 ? round.lineup_2_side : round.lineup_1_side,
+  );
+  if (other) {
+    return oppositeSide(other);
+  }
+  return sideForRoundNumber(round.round ?? 0, currentSide, latestRound, mr);
+}
+
+function lineupWonRound(
+  round: SideWinRound,
+  isLineup1: boolean,
+  prev1: number,
+  prev2: number,
+  lineupSide: Side | null,
+): boolean {
+  const score1 = scoreOf(round.lineup_1_score);
+  const score2 = scoreOf(round.lineup_2_score);
+  // Once either score moves, the delta is the source of truth — the game
+  // server has been known to report winning_side for the other team.
+  if (score1 > prev1 || score2 > prev2) {
+    return isLineup1 ? score1 > prev1 : score2 > prev2;
+  }
+  // Live rows sometimes keep both scores at 0; winning_side is the fallback,
+  // after normalizing the "T" alias the game server sends.
+  const winning = normalizeSide(round.winning_side);
+  return !!(winning && lineupSide && winning === lineupSide);
+}
+
+export function matchSideWins(
+  rounds: SideWinRound[] | null | undefined,
+  isLineup1: boolean,
+  options?: {
+    currentSide?: string | null;
+    mr?: number | null;
+  },
+): SideWins {
+  if (!rounds?.length) {
+    return { ...EMPTY };
+  }
+
+  const chronological = rounds
+    .filter((round) => (round.round ?? 0) > 0)
+    .slice()
+    .sort((a, b) => (a.round ?? 0) - (b.round ?? 0));
+
+  if (!chronological.length) {
+    return { ...EMPTY };
+  }
+
+  const mr = options?.mr && options.mr > 0 ? options.mr : 12;
+  const currentSide = normalizeSide(options?.currentSide);
+  const latestRound = chronological[chronological.length - 1]?.round ?? 0;
+
+  let ct = 0;
+  let t = 0;
+  let prev1 = 0;
+  let prev2 = 0;
+
+  for (const round of chronological) {
+    const lineupSide = lineupSideForRound(
+      round,
+      isLineup1,
+      currentSide,
+      latestRound,
+      mr,
+    );
+    if (lineupWonRound(round, isLineup1, prev1, prev2, lineupSide)) {
+      if (lineupSide === "CT") {
+        ct++;
+      } else if (lineupSide === "TERRORIST") {
+        t++;
+      }
+    }
+    prev1 = scoreOf(round.lineup_1_score);
+    prev2 = scoreOf(round.lineup_2_score);
+  }
+
+  return { ct, t };
+}