The Mets had two lefties going in their doubleheader against the Padres.
One of them gave up a lone hit in a complete-game shutout — and it wasn’t Johan Santana.
In fact, after Santana faltered in the opener yesterday, it was Jon Niese who played the role Santana seems more suited for.
Niese, in his second game back since returning from a right hamstring injury that forced him to the disabled list, pitched one of the best games in Mets history, allowing just one baserunner in the nightcap of the doubleheader, beating the Padres 3-0 after the Mets dropped the first game 4-2.
Niese surrendered just a leadoff double to Chris Denorfia in the third — the only base-runner he gave up to the weak-hitting Padre lineup. It was the 26th complete-game one-hitter in Mets’ history. They still don’t have a no-hitter.
He struck out six and didn’t walk a batter in his dominant outing.
“I really didn’t understand what was going on until after the game,” said Niese, who was told afterward that he was one bad pitch from a perfect game. “It crushed me.”
The last Met to face only 28 batters in a complete game was Shawn Estes on April 26, 2002, against the Brewers, according to the Elias Sports Bureau.
Niese’s performance made Santana’s struggles a bit easier to take. Santana failed to get a win and now has just one victory in his last eight starts — and the Mets have dropped five of the last six games he’s pitched.
Santana couldn’t find his control in the defeat that ended a nine-game winning streak at Citi Field.
“I didn’t have my command,” Santana said after pitching 6 2/3 innings and giving up four runs on eight hits. He also struck out just one.
The Mets, who also saw a four-game winning streak snapped, again failed to give him much offensive support. They have now scored a combined three runs in his last three starts.
“It’s part of the game,” Santana said. “There’s not much I can do. I just pitch and at some point everything will turn around and we’ll start scoring runs.”
After walking five in his previous start against the Padres, he issued four more in this loss and his velocity hovered in the mid-to-high 80s as he pitched for the first time in eight days because of the team’s schedule and the weather.
Santana’s fastball also didn’t have its typical jump — which made his changeup less effective.
Henry Blanco’s homer gave the Mets’ a 2-0 second-inning lead, but the Padres went up 3-2 with a run in the fourth and a pair in the fifth — while the Mets flailed at the plate, failing to reach base in their last 22 at-bats.
“It’s frustrating for him to know how good he is and what he means to this team and to not get him some wins is tough,” Jeff Francoeur said. “We’ve gotta find a way to score some runs and get him what he deserves.”
Niese got them back on track with his masterpiece that Santana at his best would be proud of.
“He had no-hit stuff,” catcher Rod Barajas said. “Something special did happen, but something more special could have.
“He was a little quieter than normal,” Barajas said. “He usually likes to talk and joke around. I didn’t hear him talk once in the dugout. I’m assuming he went out a little determined to make sure we won the series.”
He did that — and then some.
dan.martin@nypost.com