Erstad came off the disabled list today, played for half an inning, and then left the game when he aggravated a sprained left ankle.
Erstad made a diving catch in the top of the first to rob the Cubs' Mike Fontenot of a hit. When the White Sox came up in the bottom of the first, Luis Terrero pinch-hit for Erstad in the leadoff spot.
Erstad went for an M-R-I exam. Results won't be available until tomorrow.
Manager Ozzie Guillen says there was no discoloration or inflammation in the ankle.
He had been on the D-L since June First with the sprained ankle. The White Sox were 5-and-14 without him.
Erstad is batting .264 with two home runs and 21 R-B-Is in 48 games. He agreed to a one (M) million dollar, one-year contract with the White Sox in January.