Pence’s 10th homer was the Astros’ third walk-off homer in six days. Carlos Lee and Mark Loretta ended games with homers against Colorado last week.
Pence popped the first pitch from Mesa (0-1) off the left-field facade. He sprinted around the bases as fireworks exploded.
Matt Albers (2-4) shut out the Phillies in the 12th and 13th. Craig Biggio had an RBI single for the Astros, who had a bases-loaded walk for the second straight night as they won for the eighth time in nine home games.
The Phillies took a 4-3 lead to the ninth, but the Astros loaded the bases with one out against Antonio Alfonseca. Lee hit a grounder to shortstop Jimmy Rollins, who flipped to Chase Utley to start a potential game-ending double play.
The throw appeared to get Lee by half a step, but umpire Lance Barksdale called Lee safe and Biggio scored to tie it.
