San Francisco, CA (Sports Network) - After squandering the lead in the top of the ninth, Eugenio Velez hit a two-run triple in the bottom half to lift the San Francisco Giants to a dramatic 4-3 win and a three-game sweep of the floundering Arizona Diamondbacks.

Velez drove in all four runs, a career-high, for the Giants, who have won five straight games to match their season-high. Randy Winn finished 3-for-4 with a walk in the victory.

Brad Hennessey, making his first start since September 15, 2006, gave up one run on four hits in six innings of work. Brian Wilson blew his second consecutive save after he was touched for two runs in two-thirds of an inning. The comeback made a winner out of Alex Hinshaw (2-1), who recorded the final out in the ninth.

"He's (Velez) a battler," San Francisco manager Bruce Bochy said. "He's still learning about the game but he's got the tools."

Chris Young's two-run triple put the Diamondbacks ahead in the ninth. Stephen Drew added a homer for Arizona, which has lost a season-high six straight games.

Dan Haren went just four innings, yielding two runs -- one earned -- on six hits. Brandon Lyon (2-5) took the loss after he gave up two runs in 1 2/3 frames. The loss, coupled with the Dodgers' 7-2 win over the Padres late Wednesday, left the D-Backs 3 1/2 games behind LA in the NL West.

Wilson came on to protect a 2-1 lead in the ninth and issued a leadoff walk to Chris Snyder. Tony Clark worked a one-out walk and, after Drew flied out, Young hammered the first pitch he saw to the gap in right-center for a two-run triple.

In the home half, Bengie Molina had a one-out single and Aaron Rowand worked a two-out walk. Velez then tripled to nearly the same spot as Young to win the game.

"Obviously, I'd like to replay that all over again," said Lyon. "I felt pretty good being so close to winning the game, salvaging the game here. That one bad pitch right there (Velez) put a good swing on it, found a hole and that's what happened. I felt like I could have made a better pitch in that situation. I didn't do it and it cost us the game."

The Diamondbacks jumped on the board in the third on a one-out blast by Drew. After leaving the bags full in the first and stranding two runners in the second, the Giants broke through in the bottom half.

Pablo Sandoval reached first on Drew's fielding error to begin the frame and Molina followed with a single. One out later, Rowand walked to load the bases for Velez, who ripped a two-run double to right.