"I'm using Derrek's glove, and that helps," Blanco joked. "When you use a Gold Glover's glove, you expect to do well."
Left-handed-hitting third baseman Scott Moore will also get some time at first until Mabry is able to return.
Blanco said he had played some first base in winter ball. He also has experience as a third baseman, so he says he knows his way around the infield.
Mabry could be close to returning to starting duty. He played in the ninth inning of Monday night's game against Philadelphia.
REPLAY: The Cubs won their third game in a row and fifth of their last seven with a 11-6 victory at Philadelphia on Monday night. The Cubs also scored 11 runs in a victory over Cincinnati on Sunday.
Aramis Ramirez had two homers and seven RBIs Monday, and Ryan Theriot added three hits.
The Cubs won their 62nd game of the season and need one more victory to avoid 100 losses. Before this latest hot streak, the Cubs were on pace for 98 losses.
3B Aramis Ramirez, who has an "out" clause in his contract after this season, hit two homers and drove in a career-high seven runs in the Cubs' victory over Philadelphia.
LHP Sean Marshall, who pitched solidly earlier in the season, might be pitching himself out of a spot in the 2007 rotation. On Monday night, he was staked an 8-0 lead and still couldn't get through five innings. He was knocked out of the game in the fourth inning after giving up six runs in that frame. It's the third consecutive start he failed to go at least five.
CF Juan Pierre is helping his market value. He entered this week's action with 187 hits, which led the National League. The Cubs could try to sign him to a multiyear deal in the next couple of weeks, or he could end up an attractive free agent on the market during the offseason.
RHP Mark Prior continues to throw on the side, but manager Dusty Baker said he doubted Prior would be able to come back this season. Prior is currently nursing a shoulder tendinitis injury.
RHP Ryan Dempster, who has struggled in nine previous appearances, came into Sunday's game against Cincinnati with an 11-0 lead and gave up three runs, but he into Monday's game against Philadelphia with an 11-6 lead and pitched a 1-2-3 ninth. He has allowed 12 runs in his last 11 appearances. Because he is signed through 2008 as a closer, the Cubs hope he can get his confidence back in the final two weeks of the season.