Blanks singled home the winning run in the 10th inning for his career-best fourth hit, and the San Diego Padres rallied from a three-run deficit in the ninth to beat Philadelphia 4-3 on Monday.
Blanks also had a two-run single and scored the tying run on a passed ball as the Padres fought back against Cliff Lee and struggling closer Jonathan Papelbon.
When he came to bat in the 10th, Blanks knew a hit would set his career high.
"I kind of had that in the back of my mind," he said. "It's been that kind of elusive game for me. It's always fun to have those and I'm looking forward to having a lot more."
Looking for his 10th win of the season, Lee took a six-hit shutout into the ninth but lasted only three more pitches. Carlos Quentin led off with a single and went to third when Chase Headley followed with a double that ended Lee's night.
On came Papelbon, who gave up a two-run single to Blanks on his first pitch.
Jesus Guzman was hit by a pitch, but Papelbon had a chance to get out of the jam after Yasmani Grandal grounded into a double play that left Blanks at third.
Instead, Blanks scored on a passed ball by catcher Carlos Ruiz. Mark Kotsay swung and missed at a 2-0 pitch, but the ball got past Ruiz and went to the backstop. With a headfirst slide, Blanks just beat Ruiz's throw to Papelbon covering the plate.
Papelbon had converted all 13 of his save opportunities going into last week, but he's blown four of five attempts since - several in particularly frustrating fashion.
"I don't know what is worse, losing 15-0 or getting beat that way. Either way, it's a loss and it doesn't sit well with me," Papelbon said.
The Phillies were handed an opportunity to go back ahead in the 10th.
Jimmy Rollins led off with a single and Chase Utley flied out to deep center. But when Chris Denorfia tried to throw the ball back to the infield, it slipped out of his hand and trickled away for an error that allowed Rollins to go all the way to third.
Michael Young, however, struck out on three pitches against Luke Gregerson before Joe Thatcher (3-1) retired Domonic Brown on a fly to center.
In the bottom half, Denorfia drew a one-out walk from Justin De Fratus (2-1) and Quentin was hit by a pitch. Headley walked on a full count to load the bases and Blanks singled down the third base line.
"He was a guy I hadn't faced before," Blanks said. "I picked a little off the video. The first pitch was a slider in the dirt and I swung. The second pitch I was just looking to get down early and stay back enough to put something hard into play. I got enough of it and the ball hugged the line."
Utley homered and Ruiz had an RBI single for the Phillies. Rollins hit a sacrifice fly.
Eric Stults pitched a strong game for the Padres in his career-high 16th start of the season. Stults allowed two runs and seven hits in seven innings, with four strikeouts and no walks. He has given up two earned runs or less in each of his last six starts.
Ruiz and John Mayberry Jr. each had three hits. Utley hit his eighth homer in the eighth off reliever Tommy Layne, called up earlier in the day from the minors.
NOTES: Phillies 1B Ryan Howard sat out with a sore left knee. Kevin Frandsen took his starting spot. ... Phillies RHP Roy Halladay, on the disabled list since May 6 with a right shoulder injury, played catch from 50-60 feet, according to pitching coach Rich Dubee. "He wanted to start throwing with me and this is his third day doing it," Dubee said. "It looks very, very good." ... Dubee took manager Charlie Manuel's place during the pregame session with the media because Manuel was under the weather. Manuel did take his spot in the dugout at game time. ... Headley batted cleanup for the first time this season after hitting in the No. 3 spot in his previous 61 games. ... Padres manager Bud Black said 2B Jedd Gyorko, on the DL with a right groin strain since June 10, could be headed out on a rehab assignment Tuesday. "He ran the bases (Monday) and came out of it fine," Black said. "We are working through the scenario to getting Jedd out to play in a minor league game or two. And from that point we will reassess how his leg is doing and make a determination whether he joins us on the road (later in the week)." ... Phillies RHP Kyle Kendrick (6-4, 3.56 ERA) faces RHP Jason Marquis (9-2, 3.59) on Tuesday night.