(Sports Network) - Jeff Karstens will try to work out of his slump this afternoon, as the Pittsburgh Pirates and San Francisco Giants wrap a three- game series at AT&T Park.

The Pirates acquired Karstens from the New York Yankees in a deal before the non-waiver trade deadline, and the right-hander was electric in his first two starts.

Karstens pitched a total of 15 shutout innings in winning both home games, but has since allowed 15 runs in 22 1/3 innings over four road starts -- losing each one.

The 25-year-old's woes continued on Sunday versus Milwaukee, as he allowed three runs on five hits over 6 1/3 innings. Karstens has a 3.62 earned run average on the season.

He has never faced the Giants prior to today.

This afternoon's starter for San Francisco, Jonathan Sanchez, also carries a lengthy losing streak into this start.

The left-hander missed time with a left shoulder ailment before returning on Monday to face the Rockies. He gave up three runs on three hits and three walks over seven innings, but still dropped his fifth straight start and sixth consecutive decision.

Sanchez, 25, is 8-10 with a 4.50 ERA this year and 0-1 with an 18.56 ERA in three games (1 start) lifetime versus the Pirates. He has allowed 11 runs in 5 1/3 total innings against them, including a start on May 6 in which he was tagged for seven runs in 4 1/3 frames.

After losing Friday's opener, the Giants rallied for a 7-6 win on Saturday for their first victory in five games versus the Pirates this year.

Scott McClain hit a two-run homer and Pablo Sandoval went 2-for-2 with two RBI and a run scored. The win was the Giants second in three games.

Freddy Sanchez went 4-for-5 with two RBI and two runs scored and Nate McLouth added three hits and a pair of RBI for the Pirates, who have dropped two of their last three.

Pittsburgh's setback yesterday also snapped its seven-game winning streak in San Francisco.