CHICAGO -- Major League veteran Xavier Nady is among six players the Giants will officially add on Saturday, when active rosters can expand from 25 to 40 men.

First baseman Brett Pill was recalled from Triple-A Fresno; Nady and right-handed reliever Jean Machi had their Triple-A contracts purchased, while right-handers Brad Penny and Shane Loux and first baseman Aubrey Huff were activated from the disabled list.

The Giants signed Nady to a Triple-A contract on Aug. 4 to provide outfield depth. In fact, he's likely to receive some time in left field for the Giants, who have been challenged to fill the position since Melky Cabrera's suspension on Aug. 15. Nady hit .270 with six home runs, 18 RBIs and an .872 OPS in 25 games for Fresno, including .371 (13-for-35) in his previous 10 games.

Manager Bruce Bochy intends to find out whether Nady can still be productive by playing him in left field.

"He should get some starts," Bochy said, hinting that Nady might play as soon as Saturday.

Nady, 33, made the Nationals' Opening Day roster out of Spring Training but was hampered by right wrist tendinitis. He hit .157 with three home runs and six RBIs in 40 games before Washington designated him for assignment in late June.

During 10 years in the big leagues, Nady has compiled a .271 batting average with 100 homers and 390 RBIs in 920 games. He had his best season in 2008, when he hit .305 with 25 homers and 97 RBIs for the Pirates and Yankees. But injuries have prevented Nady from playing more than 100 games in every year but one (119 in 2010) since 2009.

This will be Pill's third tour of duty with the Giants, for whom he hit .222 with four home runs and 11 RBIs in 43 games. In 60 games with Fresno, Pill batted .285 with 11 home runs, 45 RBIs and a .500 slugging percentage.

Machi impressed the Giants as a non-roster invitee to Spring Training and remained effective for Fresno, posting a 2-1 record with a 3.97 ERA and 15 saves in 53 appearances.

Penny (shoulder) was 0-1 with a 6.86 ERA and Loux (neck) had no record with a 5.66 ERA for the Giants before they sustained their respective injuries. Huff (right knee) will be used off the bench, primarily as a pinch-hitter. He owns a .148 average with one home run and six RBIs in 34 games for the Giants this year.

Posey catches opener, likely to rest soon

CHICAGO -- Buster Posey will start his eighth consecutive game Saturday, but the All-Star catcher likely will get a break soon, Giants manager Bruce Bochy said after Friday's 6-4 loss to the Cubs.

It won't happen Saturday, as Bochy is planning to play Posey at first base against Chicago. Posey's durability has been an issue, given the discomfort he has experienced in his left ankle and hamstring.

All season, Bochy has made sure to rest Posey occasionally or play him at first base to spare him from the physical erosion of catching. Saturday's stint at first base will be the second for Posey in this eight-game stretch.

Bochy said that he discussed the subject with Posey on the team's flight from Houston. According to the skipper, Posey insisted that he felt fine and wanted to play. Bochy double-checked on Friday with Posey, who remained eager to play. Posey went 3-for-3 with two RBIs on Friday.

Whenever Bochy rests Posey, the skipper might face a respectful but forceful confrontation.

"I may have to take it out of his hands," Bochy said.

Worth noting

• Though Joaquin Arias started at shortstop Friday, Giants manager Bruce Bochy reiterated that left field still could be an option for the hot-hitting right-handed batter, who played one game in the outfield for the Mets in 2010. Arias entered Friday batting a Major League-high .429 in August.

• First pitch for the Sept. 9 game against the Dodgers at AT&T Park has been changed to 5:05 p.m. PT to accommodate ESPN's Sunday night telecast.

• Brandon Belt's four-hit effort Thursday in Houston was his second this month. According to the Elias Sports Bureau, only four other National League players have recorded two four-hit games in August: Los Angeles' Andre Ethier, Washington's Steve Lombardozzi, San Diego's Cameron Maybin and Angel Pagan.