MESA, Ariz. — Nick Noonan left camp quietly on March 15, his name lost amid a flurry of moves that included the reassignments of top prospects Gary Brown and Heath Hembree, and the manager's son, Brett Bochy.

But there has been nothing quiet about Noonan's late surge that could win the 23-year-old infielder an Opening Day roster spot.

Noonan, brought back to camp after Wilson Valdez was cut last week, bolstered his candidacy Monday with two sparkling defensive plays and his second two-hit game in three days as the Giants topped the Chicago Cubs 9-3.

"It seems like he's getting more and more confident and relaxed," manager Bruce Bochy said. "He's got a lot thrown at him, and I like the way he has handled it."

While it's unusual for a demoted player to be given a second shot at making the team, Bochy said the Giants never fully ruled out Noonan an option, even as he left camp with a .194 batting average.

"We tell these guys that even though they're optioned, they're not out of the picture," Bochy said.

Noonan, who started at third base Monday, still doesn't have a locker in the big-league clubhouse, but he already has earned the trust of the Giants' pitching staff.

Right-hander Ryan Vogelsong saw Noonan's defensive acumen first-hand Monday. He ranged deep into foul territory to make an over-the-shoulder grab on a first-inning popup. With the bases loaded and two outs in the fourth, Noonan dived to his left to stab a grounder by Alberto Gonzalez and made a strong throw to first to end the inning.

"He seems like he's handling himself well," Vogelsong said.

For a team that may open the season without All-Star third baseman Pablo Sandoval, Noonan's greatest strength may be his versatility. He moved to shortstop in the late innings Monday and this spring has played 29 innings there, 57 at third base and 49 at second base. That's a far cry from the output of the other infielder still vying for a backup spot, Tony Abreu, who remains sidelined by a quadriceps strain.

"Defense is so important to us — we pitch and play defense," Bochy said. "(Noonan) is a shortstop, and those guys are usually more comfortable playing third and second."

Sizemore sizzles for A's

Scott Sizemore has been waiting for this for more than a year – a four-hit game that helped the A's to a 9-7 win over the Milwaukee Brewers in Phoenix.

A knee injury that required surgery wiped out Sizemore's 2012 season on the first day of spring training last year.

He was the Oakland third baseman then, but now he's one of a handful of candidates vying for the starting job at second base. Until his four singles against the Brewers, he was hitting . 171. He scored two runs and had two RBIs.

"That's what we were waiting for," A's manager Bob Melvin said. "That's the way Scott hits, up the middle and to the opposite field. That's huge."

Sizemore had been grinding before Monday, and with the demotion of Jemile Weeks on Sunday, there was speculation about how long Sizemore could hang on.

"The way I played the first two weeks was not up to major-league levels," Sizemore said. "It's nice to see this.

"I've been seeing the ball a lot better the last four or five games, getting my timing together. I'm getting to where I can trust my swing."

That's not the case for Hiroyuki Nakajima, who is in an 0-for-21 skid and didn't play Monday, with Melvin saying the shortstop needed a day off.

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