1992 ALCS (Blue Jays @ Athletics) Game 4 [Alomar Ties Game off Eckersley in 9th] 

This game was over. The Blue Jays were down 6-1 going to 8th, and it looked inevitable that Game Five would be a pivotal swing game in the series.
The Blue Jays scored three run in the 8th, including two off of Dennis Eckersley, but, clearly, it wouldn't matter. The A's were still only three outs away from tying the series at two games each, and there was no chance the soon-to-be AL MVP and Cy Young Award Winner was going to cough up any more runs.
This game was over. And then it wasn't.
Devon White led off the Toronto 9th with a single, and then, in a battle of Future Hall-of-Famers, Roberto Alomar bested Eckersley by hitting a two-run homer to right field to tie the game at six.
In the bottom of the 9th, the A's had ample opportunity to win, but a lack of timely hitting, combined with some questionable managing by Tony La Russa (see: McGwire bunting) left the escape hatch open for the Blue Jays, which they gladly used.
Neither team scored in the 10th, but the Jays went ahead on a sac fly in the 11th, and held on for a wild 7-6 victory.
The win put Toronto up 3-1 in the LCS, and despite losing Game Five to Dave Stewart and the A's the next day, they would ultimately win the Series, and their first American League Pennant, in Game Six.