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After waiting three weeks to get back on the mound, Johan Santana lasted 43 pitches.

The New York Mets left-hander managed only four outs Saturday night in the worst start of his career, a 9-3 loss to the Atlanta Braves. He was charged with eight hits — seven singles — and a season-high eight runs in his first outing since July 20.

"I'm just trying to get my command back," Santana said. "It's been a while since I faced batters of this caliber. I just need to continue to make some progress and improve my command."

Santana (6-8) had been sidelined with a sprained right ankle, a stint on the disabled list also intended to refresh his surgically repaired shoulder. But the two-time Cy Young Award winner was hit hard for the fourth straight start and left in the second inning trailing 6-0.

Freddie Freeman then greeted reliever Jeremy Hefner with a three-run homer.

"I'm fine. It's just one of those nights I didn't execute my pitches," Santana said. "I didn't feel anything in my ankle, my shoulder, or my whole body."

The 33-year-old Santana, who missed last season following major shoulder surgery, got off to a strong start this year and pitched the first no-hitter in Mets history June 1 against St. Louis. He threw a career-high 134 pitches in that game, though, and is 3-6 with a 7.98 ERA in nine starts since.

The tailspin got especially ugly after Chicago Cubs outfielder Reed Johnson, now with the Braves, stepped on Santana's foot on a play at first base July 6. Beginning with that outing, Santana is 0-4 with a 17.36 ERA in his last four starts — by far the worst stretch of his career. He has given up 27 runs, 36 hits and six homers over 14 innings.

"I've always said that he's one of those few pitchers that hitters have to adjust to him. Maybe they have," Mets manager Terry Collins said.

Last month the Mets decided Santana had a tired shoulder, caused at least in part by landing improperly on his sore ankle. They hoped his trip to the disabled list would fully heal the ankle and recharge his shoulder. He struck out three over three scoreless innings in a rehab start Sunday for Class-A Brooklyn and then was activated on Saturday.

Collins said he thought Santana might be rusty, but he expected the longtime ace to finish the season strong.

After the game, Collins said the team might consider going to a six-man rotation to give Santana and Chris Young extra rest. Young is coming off the same shoulder surgery as Santana, to repair a torn anterior capsule.

Santana struck out Jason Heyward and Chipper Jones with two on in the first, flashing a 90 mph fastball and a useful slider. But his signature changeup was missing and the Braves took advantage on a humid, 84-degree night at Citi Field.

"When this guy was winning Cy Youngs, he had plus stuff with great command," Collins said. "You go back to April, May, June — his stuff wasn't as crisp as it was today."

Freeman stroked a two-run double past a diving Ike Davis at first base to put Atlanta ahead in the first. Dan Uggla, who is 1 for 21 with 12 strikeouts against Santana, drew a leadoff walk in the second and went to third when Paul Janish flared a soft single to center.

Opposing pitcher Kris Medlen poked a groundball single through a drawn-in infield for his first RBI this season and Michael Bourn cracked a run-scoring single to right-center. One out later, Heyward and Jones hit consecutive RBI singles to finish Santana, who never looked comfortable on the mound.

"I'd say it was rust. It's probably the best fastball I've seen since the beginning of the season," Collins said. "His command was off."

Santana tossed a ball to the third base umpire and trudged off the field to scattered boos. Sitting alone at the end of the bench, he wiped his face with a towel before Collins sat down beside him for a chat.

"It's not easy. It was a long night for me, but at least I'm back," Santana said. "The good thing is my shoulder is fine from the surgery. Right now I just have to prepare for my next start and see what happens from there."

It was the second straight start and third one this season in which Santana was knocked out so quickly he never even got to bat. He also lasted only 1 1-3 innings in his third outing of the year April 17 at Atlanta. In that game, he allowed six runs — four earned — and four hits.

"I don't see a major difference in him. There's nothing that's way off," Bourn said. "Sometimes the opposing side is better."

Santana is in the fifth season of a $137.5 million, six-year contract. He is due to make $25.5 million next year and the Mets hold a $25 million option for 2014 with a $5.5 million buyout.

Santana's deal includes a full no-trade clause. The 2014 option would become a player option if he pitches 215 innings next season. If the option is Santana's and he declines it, he would not receive the buyout.

Medlen (3-1) pitched effectively into the seventh inning for Atlanta. He struck out seven.

The surging Braves won for the 14th time in 17 games and sent the Mets to their 11th defeat in 12 home games. New York (54-60) has lost 21 of 29 overall to drop a season-worst six games under .500.

NOTES: RHP Ben Sheets (4-1, 1.41 ERA) is scheduled to make his sixth start for the Braves when they go for a three-game sweep Sunday night. LHP Jonathon Niese (8-6, 3.82) pitches for the Mets. ... Santana is 1-4 with an 8.39 ERA in his last six starts against the Braves. ... New York has lost five straight series at home.