Mercein rushed six times for 20 yards, and had two receptions for 22 yards in the "Ice Bowl"; 34 of his total yards were achieved on that game's final and famous 68 yard drive. He most notably raised both of his arms behind Bart Starr who had executed a quarterback sneak to score the game-winning touchdown with 16 seconds remaining in regulation time. Because physically aiding a teammate into the end zone is a penalty, he was indicating to the on-field officials that Starr wasn't pushed forward.
Bart Starr's game-winning touchdown in the "Ice Bowl" was made possible when Mercein rushed six times for 20 yards and caught two passes for 22 yards. The most notable moment came when Mercein signaled to the officials that Bart Starr hadn't been blocked into the end zone, as he raised his arms behind Starr after the quarterback sneak.