NEW YORK -- Right-hander Taijuan Walker made his Phillies debut against the Yankees on Monday night at Yankee Stadium, and his first inning on the mound proved costly as Philadelphia took an 8-1 loss to New York.

It was Walker’s first regular-season start since signing a four-year, $72 million contract with the Phils last December.

The reigning National League champion Phillies became the sixth pennant-winning team since 1917 to start the following season by losing their first four games. Prior to Monday, the 1984 Orioles were the last pennant-winning team to lose four straight. No pennant-winning team has lost five straight to start the following season.

Phillies manager Rob Thomson wasn’t concerned that his team has started the 2023 season on the wrong foot.

“You don’t want to start 0-4, that’s for sure,” Thomson said. “But if we lost four in a row in July, it wouldn’t be that big of a deal. So it looks a little bit worse to start the season.

“We don’t want to keep doing this. We want to keep playing, keep fighting. I know everybody is frustrated. But they keep working. They keep preparing. It’s a resilient group. It’s the same group as last year, for the most part. I expect them to come out here tomorrow, prepare and go out to compete.”

It appeared as if Walker wasn’t going to get past the first inning after throwing 33 pitches, allowing three walks and two runs. Walker acknowledged that he was “amped up” to start the game.

“I think I was trying to be too cute in that first inning, too, instead of attacking them,” Walker said. “Thirty-three pitches in any inning is going to be taxing. For it to be the first [outing] kind of sucks.”

Walker’s problems in the opening frame started with Yankees leadoff hitter DJ LeMahieu, who tripled past center fielder Brandon Marsh on a ball that looked like it should have been no more than a single. Marsh thought he was going to catch the ball, but then at the last second, he pulled up, dove for it and could only watch as it passed him for a three-base hit.

“I was trying to be aggressive, and realizing I’m not going to get there, I was trying to trust myself to get the short hop, and it went under my glove,” Marsh said. “It’s unacceptable. Things like that can’t happen, especially against a team like [the Yankees]. We have to be better than this -- plain and simple. That can’t happen and that’s on me, not on Taijuan.”

Walker then couldn’t find the strike zone, walking the next two hitters -- Aaron Judge and Anthony Rizzo -- to load the bases before LeMahieu scored the first run of the game on a groundout by Giancarlo Stanton. New York added another run that inning when Gleyber Torres hit an infield single that brought home Judge.

"I think it's contagious, for sure,” Rizzo said. “At this time, early in the year, it's kind of easy to be anxious to get hits, but when you're taking your walks and getting on base and passing it on, it definitely helps."

Walker calmed down after the slow start, throwing nine pitches and retiring the Yankees in order in the second. From that frame until he left the game with one out in the bottom of the fifth inning, Walker threw 54 pitches and allowed one run -- a solo home run to Torres in the third.

“The two-seamer was working really well [after the first inning]. We just stuck with it with the righties,” Walker said. “The rest of the way was good.”

But Walker was charged with one more run after Yunior Marte surrendered a two-run homer to Rizzo in what turned out to be a five-run fifth that put the game out of reach.

“We have 158 more [games to go],” Marsh said. “A lot of ball to play. No time to hit the panic button with four games in. I’m just frustrated about tonight.”