The opponent changed, but the Mets just carried on on Thursday.

After putting the helpless Nationals under pressure for two days in a row, coach Carlos Mendoza’s team braced itself for a bigger challenge against the NL East leaders, even with weak point Taijuan Walker on the Phillies’ mound.

Walker had, after all, pitched three innings as a relief pitcher last Saturday, helping the Phillies defeat the Mets, but that evening he served as additional batting practice.

The Mets hit four home runs against the right-hander and won 10-6 in front of 35,982 spectators at Citi Field.

The Mets, who set a franchise record by scoring at least 10 runs in the third straight game (they scored 10 in each of the last two games of a sweep of the Nationals), won their fourth straight and for the 16th time in their last 20 games.

They remained tied with Arizona in the battle for the NL’s second wild card and defended their two-game lead over Atlanta for third place.

Mark Vientos, Pete Alonso, Brandon Nimmo and Francisco Alvarez all hit home runs, while Francisco Lindor missed his fourth consecutive game due to back pain.

The Mets, who still have three home games to go, were delighted by the cheering crowd.

“It felt like a playoff game and for us it is,” Nimmo said. “We’re trying to win every single one of these games and these guys are very motivated to come out on top here. All the other teams (in the race) are playing well as well, which makes every game even more important.”

Luis Severino wasn’t at his best, but kept the Mets competitive by allowing three earned runs on five hits and two walks, as well as seven strikeouts in six innings.

It was Severino’s second consecutive start against the Phillies, and in both he allowed three runs in six innings.

Vientos and Alonso hit back-to-back home runs in the first inning to give the Mets a 2-0 lead. It was the sixth time this season that the Mets have hit back-to-back home runs.

Vientos’ goal was his 25th of the season and Alonso extended his team’s lead with his 34th.

“Right now, the way we’re playing and now that we’re in the home stretch, it’s just something you dream about in the offseason,” Alonso said. “Like, ‘Man, I want to be in that position.’ We’ve all worked really hard to get in that position and get that energy and that feedback from the fans … it just helps us play better.”

After Trea Turner hit a home run in the second inning to tie the game at 2-2, the Mets got going again in the bottom half of the inning.

Jose Iglesias hit a single first and Nimmo cleared the fence in right-center.

Severino fought through the fourth inning, allowing two hits and a walk to reduce the Phillies’ deficit to 4-3.

Brandon Marsh hit a two-out RBI single after a walk to JT Realmuto.

“The team we’re playing against is really good. They score points, so they’re not just going to go out there and not get a win for nine innings,” Severino said.

Alvarez’s rocket-like three-run victory in the fourth inning was the highlight of an inning in which the Mets sent ten batters to the plate and scored five runs.

JD Martinez was caught early in the drive and Tyrone Taylor walked before Alvarez hit a high sinker for his second home run in three games and his fourth since September 11.

But the Mets continued to gain ground in this inning. Iglesias hit a single and Nimmo’s RBI double put the Phillies in an 8-3 hole.

Vientos’ ensuing RBI single passed the baton before Alonso got walks and Jesse Winker loaded the bases. But the good times ended when Martinez threw a ball into a double play that ended the inning.

“The lineup is extremely long right now and we have a lot of guys who swing the bat well,” Nimmo said.

Danny Young allowed three runs in the seventh inning, cutting the Mets’ lead to 9-6.

The big hit of the inning was Bryce Harper’s double against Reed Garrett, which brought in two runs.

Luisangel Acuna delivered an RBI triple in the seventh inning that extended the lead to 10-6.

This was just the latest contribution from the rookie, who had hit a home run in each of his previous two games.

“Because we had the fans behind us, the atmosphere today was incredible,” said coach Carlos Mendoza. “The crowd was really good and they were into it from the beginning. The fans support the team, so we believe in it, they believe in it and it’s fun right now.”