His arm has been raised all season, but manager Jerry Manuel hasn't called on him often.
"I can't prove myself by sitting on the bench," said Liefer, who went 2-for-3 Sunday, including a three-run homer, in a 6-5 victory over Seattle.
The Sox won two of three games against the AL West-leading Mariners at Comiskey Park. Dan Wright (8-10) went 6 1/3 innings before the bullpen hung on, but not without more late-inning drama.
Jose Valentin added a homer in the third inning.
"When you don't play a lot, it's tough to stay in a rhythm," said Liefer, whose last start came Monday at Tampa Bay. "The first couple swings felt a little stale, but I kept swinging and eventually put good wood on the ball.
"I came into this year hoping to play a lot more than I have. That hasn't worked out too well."
Manuel offered a semblance of an apology for Liefer's limited playing time and indicated Liefer would take more at-bats from Thomas and other veterans in the final weeks of the season.
"I had tried to make up my mind in the second half to give him more plate appearances," Manuel said.
"But Carlos [Lee] got hot, Magglio [Ordonez] got hot, Paul Konerko got hot and Frank [Thomas] began to hit the ball well. So it became very tough to get him those at-bats. But on this trip [to Texas and Oakland], we're going to try to get him in as much as possible to keep him going."
"It was a hot day [88 degrees at game time] and he gave up a few hard-hit balls that were caught," Manuel said. "Porzio's strikeout of Olerud was very big, not only for him, but for the team."
Keith Foulke replaced Porzio after the one batter.
After McLemore stole second, Edgar Martinez singled him in. But Foulke got out of the inning with no more damage.
The loss trimmed Seattle's lead in the AL West to 2 1/2 games over Anaheim.