PITTSBURGH -- Giants manager Bruce Bochy said Friday that reliever Santiago Casilla was not available to pitch during that evening's game in Pittsburgh, barring an emergency situation.

Casilla has a blister on his middle finger. He blew a save in Washington on Thursday, allowing a double and a single and committing a fielding error as the Nationals rallied from a one-run deficit to a 6-5 walk-off victory.

"It wasn't like he was hit hard," Bochy said. "When you change closers, you're gong to have a hiccup now and then. It's gong to happen. These guys aren't going to be perfect. He's been really solid."

Casilla slid into the closer's role in April when Brian Wilson underwent season-ending Tommy John surgery. Casilla has converted 21 of 25 save situations and brought a 2.84 ERA into this weekend's series against the Pirates.

Three of Casilla's four blown saves have come in his last four appearances.

"He had a pretty good break before [Thursday]," Bochy said. "Like everybody, I think it's between pitch selection and location for him."

Bochy acknowledged that the blister might be bothering Casilla more than the reliever has let on. The manager also said Casilla would definitely be available to pitch Saturday.

Christian's big game earns another start

PITTSBURGH -- Justin Christian hasn't played much for the Giants in his second year with the organization, but the 32-year-old made the most of his start Thursday against the Nationals.

Leading off and playing right field, Christian went 3-for-5 with a double and scored three runs. He also stole second base in the sixth inning.

"I was able to put some decent swings on some pitches out over the plate and find some holes," said Christian, who earned his second straight start Friday in Pittsburgh. "Not playing in a while, it's kind of tough at times, but you just try and do the best you can."

Christian was in the lineup Thursday primarily because the Nationals started Ross Detwiler, a southpaw who has held left-handed hitters to a .122 average this season. That led Giants manager Bruce Bochy to put Christian in right rather than Gregor Blanco, who has hit .253 over 72 games this year.

Bochy was so impressed with Christian's performance that he inserted him into the lineup against the Pirates and lefty Erik Bedard in Friday's series opener. The manager said to expect more of Christian against left-handers this season.

"The way he played [Thursday], he kind of forces that issue," Bochy said.

In seven games this season, Christian is hitting .308 (4-for-13). He played 60 games for Triple-A Fresno earlier in the year, hitting .364 with 51 runs, 31 RBIs and 10 stolen bases.

"Any time you can go out there and help contribute in any which way you can, that's definitely a plus," Christian said. "I just believe in myself and know that the talent and skills that I have are still sharp."

Pirates skipper impressed by Zito

PITTSBURGH -- In discussing the Giants before Friday's series opener, Pirates manager Clint Hurdle made it clear how much he respects San Francisco starter Barry Zito.

"I was fortunate to watch this young man pitch as part of The Big Three in Oakland," Hurdle said. "There was power, there was velocity, there was spin, there was deception. [He had] a parachuting changeup, off-the-table curve, a fastball that he could throw eye-high, and [he could] throw the breaking ball off it."

Zito spent the first seven years of his career in Oakland, where he won the American League Cy Young Award and was voted to three All-Star Games. As a member of the A's, Zito posted a 102-63 record and 3.55 ERA.

But as Giants fans know, Zito has struggled in orange and black. After signing a seven-year deal worth $126 million, Zito is 49-67 with a 4.47 ERA during the six years he's spent in San Francisco.

"What he's had to do is re-create himself, and I think it's taken him some time, but he's doing a pretty good job of it now," Hurdle said. "He'll still be challenged with command from time to time. Playing with discipline can work against him, and you can help yourself with some walks. Get him down in some counts where he's got to come in."

Zito brought a 6-6 record and 3.84 ERA into his Friday start against the Pirates. He has racked up 52 strikeouts to go with 45 walks and threw a shutout in his first start of the season, something he hadn't done since 2003.

"He will still throw that breaking ball off the fastball up in the zone. He's cutting the ball more than he did in the past, in on right-handers and away from left-handers," Hurdle said. "The curve is his bread and butter, always has been and always will be."

Worth noting

• Entering Friday, the Giants were 3-8 in their last 11 road games and had lost four straight away from AT&T Park. Their away record this season is 19-22.

• All-Star starter Melky Cabrera needed just four hits this weekend to tie Rich Aurilia for the most hits in Giants history prior to the All-Star break. In 2001, Aurilia picked up 120 hits before the break.

• Over their last nine games entering Friday, Giants hitters were batting a meager .188 (17-for-90) with runners in scoring position. Overall, San Francisco was hitting .223 in those situations, third worst across the Majors.