SAN FRANCISCO -- Jeremy Affeldt threw a light bullpen session Friday afternoon and Giants manager Bruce Bochy said the left-handed reliever's sprained left hamstring is improving.

"Jeremy's coming around," Bochy said. "He feels much better. Hard to say what day [he'll return]. It could be [Saturday] -- that's how much he's improved -- or it could be a couple more days."

Bochy said Affeldt would not be used in Friday's series opener against Arizona, but depending on how Affeldt feels Saturday, he could be available for Saturday's game.

Affeldt (2-3, 3.12 ERA in 17 appearances) sprained his hamstring Sunday against the A's in the eighth inning while trying to field a sacrifice bunt by Daric Barton, who led off the inning. Affeldt faced two more batters before leaving the game.

Lincecum has positive bullpen session

SAN FRANCISCO -- Giants ace Tim Lincecum threw his regular bullpen session Friday afternoon, which Giants manager Bruce Bochy said went well.

Lincecum, the two-time reigning National League Cy Young Award winner, has been experiencing uncharacteristic struggles in his past two outings. On Wednesday against Washington, Lincecum lasted only 4 2/3 innings, allowing six runs on six hits in a 7-3 loss to the Nationals. That poor outing followed Lincecum's May 20 start against Oakland, where he gave up five runs on five hits in a no-decision.

During his recent stretch, Lincecum has struggled with his command -- walking five batters in each of his past three starts -- and focus. On Wednesday, the Nationals stole four bases on Lincecum, three of which came in the three-run fifth.

In his bullpen session Friday, Lincecum practiced a few pickoff moves with dummy runners in AT&T Park's left field.

Bochy said he expects Lincecum to bounce back in his next start Monday against Colorado, simply because that's what Lincecum -- and other great pitchers -- do.

"Normally they don't stop working and they get after it," Bochy said of what he's noticed about star players who struggle. "They don't get down, they put those [bad starts] behind them. That's what separates your average player from your great player is your ability to put the bad outings behind you and move on."

DeRosa hopes to 'grind it out' with wrist

SAN FRANCISCO -- Mark DeRosa's plan is simple: He's determined to try to play for as long as he can this season, braving the discomfort in his injured left wrist.

Then when he can't play anymore, whether the season has passed or just a few weeks, he'll undergo surgery.

In DeRosa's perfect world, he'll try swinging a bat Saturday or Sunday after waiting for the effects from a cortisone shot to ebb. Then he'd go on a brief Minor League injury rehabilitation assignment early next week. Finally, he'd leave the 15-day disabled list in time to join the Giants in Pittsburgh, where they begin a two-city trip next Friday.

"Hopefully I'll get activated and grind it out until I can't grind it out," the outfielder-infielder said Friday.

DeRosa's course of action was cemented Thursday by Dr. Thomas Graham, the Baltimore-based wrist specialist DeRosa visited for a second opinion. Though the numbness in the index and pinky fingers of DeRosa's left hand has decreased, Graham confirmed that the 35-year-old will ultimately need surgery, which would require three months of recovery.

Graham told DeRosa that his ability to play will be determined by his pain tolerance and sheer effectiveness on the field.

"You saw how effective I was the first go-round," said DeRosa, who hit .194 in 26 games before being sidelined. "That being said, the trainers and I have done everything for the last two weeks to put it in great position to at least give it a try. That's what I'm going to do."

Posey may get callup from Giants today

SAN FRANCISCO -- According to reports from the San Jose Mercury News and AOL Fanhouse, Buster Posey may be called up for tonight's game against the D-backs. The reports indicated the Giants' top prospect would start at first base.

General manager Brian Sabean hinted on Thursday on the KNBR weekly show he shares with president Larry Baer that Posey could soon join the big club.

"I think it's possible," Sabean said. "We discussed it before and after [Thursday's] game."

With infielder/outfielder Mark DeRosa (wrist) and shortstop Edgar Renteria (hamstring) on the disabled list, Sabean said Posey could find a home at first base, where he has started the past two games at Triple-A Fresno.

Incumbent first baseman Aubrey Huff would shift to left field if a move were to happen.

Entering Friday, Posey was hitting .343 (58-for-169) with six home runs, 31 RBIs and 12 doubles in 46 games. He also has drawn 27 walks and struck out 30 times for a .438 on-base percentage.

"He's really improving," said Sabean, who spent two days in Fresno this week. "I just don't know what to make of a .344 average and how that translates to [big league] pitching."

In seven games with the Giants last season as a late-season callup, Posey hit .118 (2-for-17) with four strikeouts.

Giants talking to Burrell about possible deal

SAN FRANCISCO -- Giants manager Bruce Bochy confirmed Friday that the Giants are in discussions to sign outfielder Pat Burrell.

Burrell, 33, was designated for assignment by Tampa Bay on Saturday after beginning the season hitting .202 with two home runs and 13 RBIs in 24 games, all at designated hitter.

Bochy said he has not personally been in contact with Burrell and did not know where the discussions stood about three hours before the Giants opened a three-game series against Arizona.

He also declined to speculate where Burrell, if indeed signed by the Giants, would fit into the lineup.

"Right now we have our guys," Bochy said. "I can't be concerned about another guy right now."

Burrell is a .253 lifetime hitter with 267 career home runs and 904 RBIs.