SAN DIEGO -- Minutes after the Mets lost a 4-0 game to the Padres on Monday, Pete Alonso sat at his locker, as he often does, writing longform notes on the pitchers he faced in the game. On this day, his book included an entry on Chris Paddack, the brash, flame-throwing right-hander who blanked the Mets over 7 2/3 innings.

Before the game, Paddack relished the chance of facing Alonso, calling him “a great player” in an interview with The Athletic, but adding: “I’m coming for him. We’ll see Monday who the top dog is.”

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Paddack then backed up his words not only with strikeouts, but additional bluster. Whiffing Alonso twice in his first two at-bats, Paddack pumped his fist animatedly both times in celebration. The Mets’ dugout took notice, with at least one player saying privately that the team did not appreciate Paddack’s gestures.

Alonso made his grievances public.

“I know what he said,” Alonso said. “To me, it doesn't sit well. And for us as a team, it definitely sucks. It definitely sucks after this one. Definitely a sour taste for sure. But I don't think one game necessarily tells the whole story. This season is a marathon, not a sprint.

“He’s allowed to say what he wants. He wanted me and he got me tonight, simple as that. It kind of fired me up and it was going to be a good matchup, and I didn't answer the bell. I had a couple guys on base when I was up and I didn't do the job tonight. It's not good. That's not a good feeling. It's a really tough pill to swallow.”

Paddack’s primary issue appeared to be not with Alonso personally, but with the National League Rookie of the Month award he won after hitting nine home runs with a 1.024 OPS in March and April. Paddack also had a chance at that hardware, going 2-1 with a 1.91 ERA over the same timeframe, but the baseball writers who vote on the award ranked him below Alonso.

And so a feud was born, even if Alonso is not entirely sure how he found himself in the middle of it.

“If he was upset about it, I'm assuming he could have been a little jealous,” Alonso said. “I'm happy to win it. If he was mad about that, there's five other months. … Also, he said something about winning the Rookie of the Year. That would be nice, but I'm trying to win a World Series.”

For a Mets team sitting on four straight losses and the National League’s 11th-best record, that goal has rarely seemed quite so distant as it did late Monday, after Paddack outpitched Jacob deGrom. In his second consecutive quality start, deGrom retired nine consecutive Padres to open the game, and allowed just two runs -- a Hunter Renfroe solo homer and a Ty France sacrifice fly -- in seven innings. But the Mets struck out 11 times against Paddack, mustering only four hits. Alonso went 0-for-4 with three strikeouts. Michael Conforto and Wilson Ramos were both 0-for-4 with two whiffs. The only Met to make it to scoring position was deGrom.

When asked afterward about Paddack’s performance, deGrom shrugged and said, “His stuff was OK.” Regarding Paddack’s on-field celebrations, Mets manager Mickey Callaway declined comment other than to say, “He’s got confidence.”

Alonso’s words rang stronger and more direct. Partly because of his personal grudge and partly due to the Mets’ four-game losing streak, Alonso called the Mets’ Tuesday rematch against the Padres a must-win game -- a phrase rarely uttered in baseball clubhouses in the first week of May, but one the Mets feel strongly about as they fall ever downward in the standings.

"Obviously, I saw what he said and didn't take kindly to it,” Alonso said late Monday. “But this isn't about me and Chris Paddack. This is about the New York Mets versus the San Diego Padres. There's more to it than just a 1-v-1 battle because this is a team effort. We've got to get them tomorrow. It's a must. We need to win tomorrow."