Martin's poor throw in the 11th inning set up the winning run in the Pittsburgh Pirates' 4-3 loss to the Chicago Cubs on Sunday.
There were runners on first and second with no outs when Martin tried to pick off Anthony Rizzo at second and the ball sailed into center field. Rizzo and Alfonso Soriano each moved up a base on the veteran catcher's first error since Sept. 11 for the New York Yankees at Boston.
"I lost grip coming up on the transfer," Martin said. "Sometimes you can get the grip as you're going, but I just never really had any grip on the ball and it took off."
After Luis Valbuena was walked intentionally, pinch hitter Dioner Navarro drove in Rizzo with a sacrifice fly off Bryan Morris (4-3).
Pittsburgh (53-34) has dropped three of four to fall into a tie with St. Louis for the NL Central lead and the best record in baseball. But Pirates manager Clint Hurdle was quick to defend Martin and pointed to some other key situations that hurt his club.
"We're playing to win," Hurdle said. "If you've watched that guy play all year, you just move on. Throw against the bag and he's out. What hurt us earlier was the fourth and sixth innings with a runner at third and we weren't able to score them. Those were things that kind of challenged us a little bit."
The situation in the sixth was particularly glaring, coming with the game tied at 2. The Pirates had runners on second and third with one out, but Jordy Mercer bounced into a fielder's choice that retired Pedro Alvarez in a rundown between third and home. Pedro Strop then came in and struck out pinch hitter Gaby Sanchez to end the inning.
The Cubs grabbed a 3-2 lead when Scott Hairston connected for a pinch-hit solo homer against Tony Watson in the eighth inning. It was Hairston's eighth homer.
The Pirates were down to their last strike in the ninth when Starling Marte drove a 3-2 pitch from closer Kevin Gregg over the wall in center for his ninth homer.
"We never quit, that's something you can't teach," Pittsburgh starter A. J. Burnett said. "Just play until the last out's made and that's what we do. You saw Marte, he fouled off some tough pitches, he battled and you saw what happens."
It was Gregg's second blown save in 17 opportunities. He began the inning with consecutive strikeouts against Jordy Mercer and pinch hitter Travis Snider.
"We were one strike away there," Gregg said. "I made some good pitches in to him, made him conscious of the ball in. I felt like I made a pretty good pitch away from him and he did a good job of hitting and going to get it."
But Navarro rescued Gregg in the 11th inning, and Matt Guerrier (3-4) pitched two scoreless innings for his first win with Chicago.
Burnett came off the 15-day disabled list after being sidelined by a strained right calf and pitched five solid innings. He allowed two runs, one earned, and three hits.
"Nothing not to like," Hurdle said of Burnett's performance. "The ball came out of his hand very crisp, pitched efficiently."
NOTES: RHP Ryan Reid was optioned to Triple-A Indianapolis to make room for Burnett. ... The Pirates start a six-game homestand Monday that includes three-game series against Oakland and the New York Mets. Monday's game features a pair of All-Star pitchers, with Jeff Locke (8-1, 2.12 ERA) facing the A's Bartolo Colon (11-3, 2.78 ERA).