San Francisco @ Chicago preview

Last Meeting ( Jun 28, 2011 ) San Francisco 13, Chi. Cubs 7

THE STORY: The lowest-scoring team in the major leagues meets the most generous pitching staff in baseball when San Francisco comes to Chicago on Tuesday for a day-night doubleheader with the Cubs. Chicago finished the weekend with back-to-back defeats in Kansas City before coming home Monday to post a 7-3 win over Colorado. The Giants arrive off a weekend sweep of Cleveland that extended their win streak to five games.

TV: 8:05 p.m. ET, Comcast Sports (San Francisco), Comcast Sports (Chicago)

PITCHING MATCHUPS: Giants LH Barry Zito (0-1, 6.23 ERA) vs. Cubs RH Rodrigo Lopez (0-1, 6.59 ERA).

Zito was activated from the disabled list Saturday after being sidelined by a foot injury since April 14. He was not particularly sharp in his three April starts, walking eight while striking out just six in 13 innings. In six career starts against the Cubs, Zito is 1-3 with a 4.84 ERA. The former American League Cy Young winner isn't likely to rejoin the Giants' rotation for long – thanks largely to the emergence of Vogelsong. Zito is expected to be moved to the bullpen after Tuesday's spot start.

Lopez will be making his second spot start of the season, and he's hoping it goes better than his first, when he surrendered six runs on 10 hits in just 4 2/3 innings against Houston on May 30. He has made nine appearances out of the bullpen since, giving up four runs in 10 innings. Lopez is 0-3 with a 6.97 ERA in six career starts against the Giants. He has been hit hard by 3B Pablo Sandoval (6-for-12, 4 2B, HR, 6 RBIs) and Miguel Tejada (11-for-23, 3 2B, HR).

ABOUT THE GIANTS (44-33): Despite having scored fewer runs than any team in baseball, San Francisco has managed to remain atop the National League West thanks to an outstanding pitching staff that ranks fourth in the major leagues with a 3.21 ERA. All five starters have ERAs of 3.84 or lower, and the middle relief tandem of Sergio Romo (2.25, 12 holds) and Javier Lopez (2.45, 13 holds) has been extremely reliable in paving the way for closer Brian Wilson (5-1, 2.50 ERA, 23 saves). The Giants have given up just six runs during their current five-game win streak.

ABOUT THE CUBS (32-46): Chicago found its groove at the plate on Monday, with 3B Aramis Ramirez and 1B Carlos Peña each clubbing a pair of home runs against the Rockies. Peña got off to a particularly rough start this season, batting .159 in April with no home runs and just five RBIs, but he already has nine homers in June, including six in his last nine games. He has picked up the slack for LF Alfonso Soriano, who hit 10 homers in April but has just four since. SS Starlin Castro has been a spark at the top of the lineup, ranking among the league leaders with a .325 batting average.

FINAL PITCH: Tuesday's second game is a makeup for the May 15 contest that was rained out. The two teams have split their two previous meetings this season.