NEW YORK -- The Mets called up right-handed reliever Manny Acosta from Triple-A Buffalo on Tuesday in response to the heavy workload manager Terry Collins has been forced to place on his bullpen this week.

With three-inning efforts from starters Johan Santana and Miguel Batista on Friday and Saturday, and a 12-inning game on Sunday, New York's relievers had to work 17 innings during their three game series against the Dodgers. Monday's 10-inning series opener against Washington didn't help the situation.

"We've got an issue, and we need help," Collins said. "We have to nail some fresh arms down there so we don't kill guys."

Acosta, 31, was designated for assignment on May 29 after starting the year 1-2 with an 11.86 ERA in 22 innings. In 28 innings with Buffalo since the demotion, Acosta is 0-1 with a 2.25 ERA and 25 strikeouts. He threw 21 pitches over two innings of relief in a Minor League appearance on Monday, but Collins said the right-hander was still be available out of the bullpen on Tuesday.

"He's pitching very well," Collins said. "He's had, I think, only a couple bad outings in Buffalo, but [Buffalo manager] Wally [Backman] told me 'We all see that plus stuff.' When he keeps it down and pitches come in like he's supposed to, he's very, very good."

Lucas Duda and right-hander Pedro Beato were optioned to Buffalo on Tuesday to make room on the Major League roster for Acosta and top-prospect Matt Harvey.

Valdespin sets Mets record for pinch-hit homers

NEW YORK -- It's a shame Jordany Valdespin can only serve as a pinch-hitter once per game.

Valdespin hit a pinch-hit home run to lead off the eighth inning Tuesday night at Citi Field, his fifth pinch-hit homer this season, a franchise record. Mark Carreon and Danny Heep both held the previous team record of four, accomplished in 1989 and 1983, respectively.

"It's great. I want to have a long career here, so the only thing I have to say is keep it going," Valdespin said. "Keep it going and play hard."

Valdespin drove a 2-1 pitch from Ryan Mattheus into the Nationals' bullpen in right-center field. He has been an efficient option for manager Terry Collins off the bench -- he is 6-for-24 as a pinch-hitter this season -- and has provided the Mets with immediate offense on numerous occasions.

"I've always thought one of the things he always has created, by putting him in the game at certain times, he has the chance to do some damage, and he's done that," said Collins.

Valdespin's five pinch-hit home runs are the most in the Majors and are tied for the most in a single season since Matt Stairs hit five with Philadelphia in 2009.

Francisco to pitch for Binghamton on Wednesday

NEW YORK -- Mets closer Frank Francisco will begin his rehab assignment with Double-A Binghamton on Wednesday, starting his rehab one day later than initially planned.

Francisco, who has been on the disabled list since June 23 with a strained left oblique, was to begin the assignment on Tuesday with Class A Brooklyn, but discomfort in his right knee -- that ultimately required a shot -- pushed his schedule back a day.

Francisco said Wednesday that he felt no pain in his knee and that any soreness in his oblique had subsided. He threw a 40-pitch bullpen session at Citi Field on Tuesday with no discomfort.

"We need him back very badly. Our bullpen has had a tough time," manager Terry Collins said. "He's the one addition. You're trying to find bullpen help, we've got bullpen help. It's in-house. We just got to get him back out there."

Collins said the Mets opted to perform the injection on Monday to prevent future flare-ups. He said that despite an overworked bullpen -- New York's 'pen pitched a combined 17 innings of relief in the team's weekend series against the Dodgers -- the focus remained on Francisco's late-season availability.

"What's two more days right now, as opposed to saving us a week down the road here when we really need him?" Collins said. "We're going to get it done, and I'd think in the next five or six days, Franky Francisco will be in our clubhouse."

Collins gives Tejada break from starting lineup

NEW YORK -- Ruben Tejada got a day off on Tuesday to rest his spiked right shin, suffered in the 10th inning of Monday night's 8-2 loss to Washington.

Tejada was spiked by a sliding Roger Bernadina at second base after the shortstop failed to catch a throw from pitcher Tim Byrdak. Tejada went to the ground for a few minutes but stayed in the game despite two noticeable gashes.

Tejada didn't need any stitches and said that he could play if needed, but manager Terry Collins opted to play it safe in preparation for Wednesday's 12:10 p.m. ET matinee.

Mets ink reliever Hansen to Minors deal

NEW YORK -- The Mets signed right-handed pitcher Craig Hansen -- who most recently pitched with the Pirates in 2009 -- to a Minor League contract on Tuesday that will extend through next season. He will report to Port St. Lucie, Fla., to begin a throwing program.

Hansen, who was taken 26th overall by the Red Sox in the 2005 First-Year Player Draft, made his debut later that year and appeared in 38 games in 2006. He spent the entire 2007 season with Boston's Triple-A affiliate, and after rejoining the Red Sox in 2008, he was traded to Pittsburgh halfway through the season.

Over four Major League seasons and 95 appearances, Hansen has compiled a 4-9 record and 6.34 ERA.