SAN FRANCISCO -- The Rockies' Chris Iannetta has fun before games by trading his catcher's mitt for a fielder's glove and pretending he's an infielder, taking ground balls.

Tuesday night, he had an absolute blast after being pressed into playing third base -- and blasted a home run and a double -- during just the Rockies' second victory in nine games, 3-2 over the Giants at AT&T Park.

"It's fun. It's baseball -- I'll remember this game for the rest of my life," Iannetta said.

It was such an odd contest that Iannetta's moving to third for the first time since collegiate summer league play might not have even been the most impressive case of filling in. Third baseman Garrett Atkins moved to second -- a position he'd never played at any level -- and made a couple of game-saving plays.

The scrambling began because infielder Jeff Baker suffered a broken blood vessel in his right middle finger while warming up for the game and shortstop Troy Tulowitzki suffered an upper left quadriceps strain during the first inning.

It wasn't the way Rockies manager Clint Hurdle wanted his players to incorporate his current favorite slogan: "Play the game, don't work the game." That's exactly what happened as Iannetta and Atkins played with a smile, and right-hander Aaron Cook (4-1) threw seven strong innings and once again made everyone happy by ending a losing streak -- this one four games.

To cap off the strangeness, Iannetta scored the winning run in the seventh on a balk called against Giants starter Tim Lincecum (4-1).

"It just goes to show you when you think you've got control of something, really, what do we really have control of?" Hurdle said. "At the end of the day, you really don't."

Tulowitzki suffered pain on a first-inning throw to first base that Todd Helton dropped for an error. Later in the inning, Tulowitzki pulled up before reaching an Aaron Rowand bouncer, which became an RBI single that gave the Giants a 2-1 lead, and had to leave.

Iannetta and Atkins went to their unfamiliar places and Clint Barmes moved from second to short.

Iannetta led off the top of the third with a home run to center off Lincecum. The 2-for-4 night brought Iannetta to .522 (12-for-23) with three home runs and eight RBIs in eight games at AT&T Park.

"Limited opportunities, that's about it. .. I don't really know what it is," Iannetta said.

Cook gave up 10 hits but forced 14 ground-ball outs, meaning Iannetta -- who said third was his primary position in Little League -- and Atkins had to help.

Atkins ranged to his left to grab a Brian Bocock grounder, then spun and threw to first to end the sixth with a runner at third.

"I didn't think he had a chance at it -- he went a long ways for that ball," Helton said.

The Giants' Randy Winn opened the seventh with a double and tried to take third on Fred Lewis' grounder, but Barmes threw to Iannetta, who applied the sweep tag. Cook would finish the inning by fanning Ray Durham for one of his three strikeouts.

With Jose Castillo at second and one out in the bottom of the ninth, Atkins battled the tough AT&T Park winds to grab a Winn popup, then Brian Fuentes struck out Daniel Ortmeier for his second save.

Atkins said when the position change occurred, he had to check with Mike Gallego, who coaches infielders, since he wasn't sure where to line up. But after the game, teammate Ryan Spilborghs was shouting Atkins' sixth-inning play could have been made only by "G" [Atkins] and "O-Dog" [Diamondbacks Gold Glove second baseman Orlando Hudson].

"How many times will I have a chance to play second base in the big leagues?" said Atkins, who participated in two double plays -- and extended his hit streak to 14 games. "That'll probably be my only time. I just tried to have fun.

"I was thinking this would be the kind of game we're going to win. Everybody was loose at that point, probably what we needed."