NEW YORK -- The Philadelphia Phillies enter Sunday with a better record in August than the New York Mets. The Mets, however, are feeling far better than the Phillies heading into the finale of a three-game series at Citi Field.

The Mets will look to complete a sweep of the Phillies - and continue their surge in the race for the National League's second wild card - when the two teams square off Sunday afternoon.

New York hit four homers for the second straight game on Saturday in a 12-1 rout. The Mets have outscored the Phillies 21-5 in the first two contests to improve to 66-63 overall and pull within 2 1/2 games of the St. Louis Cardinals for the second wild card.

The Mets, who are 12-13 this month, have scored 50 runs in the last seven games, during which they have gone 6-1. The current hot stretch follows a 34-game stretch in which New York went 13-21 and scored three runs or fewer 18 times.

"Just the nature of the game," Mets manager Terry Collins said. "There's some days, there's some weeks you're red-hot and others you can't hit anybody."

The Mets have been ignited by the return of Jose Reyes, Asdrubal Cabrera and Yoenis Cespedes, all of whom were on the disabled list earlier this month. The trio, which occupied the top three spots in the lineup in each of the last two games, is a combined 13-for-23 with five homers, nine RBIs and 10 runs scored against the Phillies.

"It looks like a completely different team," Collins said.

Manager Pete Mackanin has seen a completely different team over the last five games as well, a stretch in which Philadelphia has gone 1-4 while being outscored 42-11.

"The funny thing about it is we're 11-11 in the month of August, so it's hard to figure out," Mackanin said.

Phillies right-hander Vince Velasquez gets the task of trying to figure out the Mets on Sunday. New York has scored 62 runs in 11 games against the Phillies this season.

"We've just got to regroup, put these two games behind us," Mackanin said. "It's like (the Mets) know what's coming. They just seem to feast on our pitching."

Velasquez fell to 0-4 in seven starts since the All-Star break in his most recent outing on Aug. 21, when he gave up five runs over six innings as Philadelphia fell to the Cardinals, 9-0.

Mets right-hander Robert Gsellman is scheduled to make his first major league start for New York. It will be the second career appearance for Gsellman, who won his debut on Tuesday by throwing 3 2/3 innings of scoreless relief in place of injured left-hander Jonathon Niese in the Mets' 7-4 victory over the Cardinals.

Gsellman is taking the rotation spot of Niese, who is expected to miss the remainder of the season after undergoing left knee surgery on Thursday.