Early fan voting shows that Troy Tulowitzki is a lock to be the National League's starting shortstop in the All-Star Game. And given his numbers and heroics, he certainly must be an early-season MVP candidate as well.

Tulo rescued the Rockies with a two-run homer in the eighth inning Tuesday night, driving in Carlos Gonzalez, as the Rockies beat the Reds 5-4. Tulowitzki stepped into reliever Sam LeCure's 3-2, 89 mph fastball, driving it on a string into the left-field seats at Great American Ballpark.

"That's a big win," manager Walt Weiss said after the Rockies notched just their second road win of the season when trailing after seven innings. "To win like that on the road, late against a really good club, that's a big one. That was a big-time home run by a big-time player. It doesn't get any more clutch than that."

Tulo's blow also erased an embarrassing balk by reliever Edgmer Escalona in the seventh inning that appeared would cost the Rockies the game.

It was Tulowitzki's 13th homer. He now has 45 RBIs in 53 games. It was his 10th go-ahead RBI on the road and his seventh game-winning hit of the season.

"When (LeCure) walked CarGo, I figured he was going to have to challenge me," Tulowitzki said. "He didn't want to walk two in a row and put a runner in scoring position. He left it up, and I happened to put a good swing on it. I hadn't been taking good swings all series, so it was nice to come through."

A fan reached out and gloved Tulo witzki's homer, but a quick video review by the umpires confirmed that Tulowitzki's blast crossed the yellow line above the left-field wall.

Escalona's troubles began when Reds pinch-hitter Xavier Paul clubbed a one-out double to right and moved to third on Shin-Soo Choo's single. Appearing rattled, Escalona faked a pickoff throw to third, and then faked a throw to first. Problem was, a rule change during the offseason eliminated the fake pickoff to third base.

Balk.

It was an easy call for home-plate umpire Gary Cederstrom, and it sent Paul jogging to home with the go-ahead run.

"I figured it would happen to someone this year, but I didn't figure it was going to be someone on our own team," Tulo witzki said. "I think after you win the game, it's going to be talked about a lot less than if it had lost the game for us."

Escalona said he became confused when he got a pickoff sign from catcher Yorvit Torrealba. Escalona said he simply forgot the rule. So he was understandably thrilled, and relieved, when Tulo cranked his home run.

"When their guy walked CarGo, I said: 'God protect me. You have to take care of me,' " Escalona said. "If we lost, everybody was going to be mad at me. I was saying, 'Give me a home run.' When Tulo hit the ball, I was like, 'Yeah!' and I went crazy."