San Francisco @ Houston preview

Last Meeting ( Aug 20, 2011 ) San Francisco 5, Houston 7

THE STORY: The San Francisco Giants could always fall back on their starting pitching. Now that is in question. Jonathan Sanchez has been scratched from his scheduled start on Sunday, forcing the Giants to scramble. San Francisco may be riding a three-game losing streak but at least they managed to score a few runs on Saturday, something that has become increasingly difficult. The Houston Astros have matched their longest winning streak of the season at four games and continue to get contributions from a string of rookies as they attempt to finish the season on a positive note. The Astros will try to sweep their first series since June 1 when they host the Giants in the finale of a three-game set on Sunday afternoon.

TV: 2:05 p.m. ET, CSBA (San Francisco), FSH (Houston)

PITCHING MATCHUP: Astros RH Henry Sosa (0-2, 6.00 ERA) vs. Giants LH Dan Runzler (1-2, 6.64 ERA).

Acquired from the Giants in exchange for infielder Jeff Keppinger before the trade deadline, Sosa was immediately brought to the major leagues by Houston and will get an opportunity to make a mark in the starting rotation the rest of the way. So far it has not quite worked out for the 26-year old Dominican, who has allowed a total of eight runs and 13 hits in 12 innings while absorbing the loss in each of his first two chances.

Sanchez was scheduled to go on Sunday but was scratched due to a sprained left ankle suffered in a start at Atlanta last Tuesday. Runzler was inserted in Sanchez's place. The 26-year old has pitched exclusively in relief for San Francisco but worked as a starter at Triple-A Fresno before being recalled this week. Runzler went 1-3 with a 4.02 ERA as a starter for the Grizzlies.

ABOUT THE ASTROS (42-84): Houston’s only other four-game winning streak this season came from May 30-June 2 and was done with a largely different lineup. Gone are former anchors Michael Bourn, Hunter Pence and Keppinger, who have been replaced by a steady stream of young players. The most promising of the crop is diminutive second baseman Jose Altuve, who recorded his first major-league homer on Saturday when he led off the bottom of the first inning with an inside-the-park blast off the wall in left-center. Altuve finished the contest 3-for-5 with two runs scored and is hitting .327 in 28 games. Fellow rookie J.D. Martinez added a homer and four RBIs on Saturday and has five homers in 20 games.

ABOUT THE GIANTS (67-60): San Francisco squandered strong starts by Tim Lincecum and Ryan Vogelsong in getting shutout two nights in a row. The losing streak hit three games on Saturday when Madison Bumgarner ended the string of strong outings by getting lit up for seven runs - six earned - and 11 hits in 6 2/3 innings. At least the offense made a small dent, totaling five runs and 10 hits in the contest. The only thing going in the Giants’ favor right now is that the Arizona Diamondbacks keep losing, holding the deficit in the NL West at 2 1/2 games. San Francisco has lost 16 of its last 22 games overall.

FINAL PITCH: Carlos Beltran is eligible to come off the disabled list when the Giants begin a 12-game homestand on Tuesday. San Francisco’s big trade deadline acquisition, Beltran has been out since Aug. 7 with a strained right hand. He took on-field batting practice for the first time since the injury on Saturday.