“He’s been a very, very pleasant surprise,” manager Willie Randolph said. “So far, I like what I see.”

Asked whether Williams has a chance to make the playoff roster, Randolph said the lefty is an option — just like everyone else on the staff.

Delgado hit a tiebreaking home run off John Smoltz (12-8) in the sixth, and Green added his first homer with New York in the eighth.

Brian McCann homered and leadoff batter Willy Aybar had three hits for the Braves.

“I just don’t understand. But I guess you give credit to the other pitcher,” Smoltz said.

A rainout Tuesday night forced Atlanta to play yet another doubleheader. The Braves played two games each on Saturday and Sunday in Philadelphia, splitting both twinbills. They have a day off on Thursday.

With the score tied at 1 in the opener, Paul Lo Duca singled leading off the sixth. Delgado then drove a 2-2 pitch over the right-field fence to give him 36 homers and 100 RBIs. Smoltz threw his head back in frustration.

Williams (5-3) cruised through six innings on only 72 pitches, allowing five hits and no walks.

Acquired from Cincinnati on May 25, Williams was sent to Triple-A Norfolk, where he was on the disabled list from June 9 to July 29 with a strained left shoulder. He made his Mets debut on Aug. 19 against Colorado.

“In this game you don’t get too many opportunities and you better take advantage of them or they’re going to find someone else,” Williams said. “If I pitch well enough, hopefully I’ll play here next year. And if they don’t have me on the playoff roster, so be it. I’m just trying to finish up strong and put myself in a position to hopefully make that roster.”

Pedro Feliciano and Guillermo Mota each worked a scoreless inning before Billy Wagner got three quick outs for his 35th save in 40 chances.

Notes: It was New York’s first doubleheader sweep at home since Aug. 15, 2000, against Colorado. ... Braves 2B Marcus Giles went 2-for-4 in the nightcap, his first action since medical tests Sunday in Atlanta determined he has a healthy heart and he was cleared to resume playing. Last weekend in Philadelphia, Giles was told he might have a heart defect.

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