The San Diego Padres are in a must-win spot in the National League Division Series, and they'll have to get there without one of their most improbable comeback stories. The club placed right-hander Walker Buehler on the paternity list on Saturday, according to MLB's official transactions log, pulling him off the roster as San Diego trails the Milwaukee Brewers 1-0 in the best-of-five series.

San Diego filled Buehler's postseason roster spot the same day by activating right-hander Randy Vásquez, the same transaction report shows. The moves came a day after the Brewers took Game 1 at American Family Field, 3-2, on home runs from Jackson Chourio and William Contreras.

A placeholder, not a replacement

Buehler isn't expected to miss long. In its Game 2 preview, MLB.com reported that Vásquez is available for long relief on Sunday "with no limitations," since he will "presumably be taken off the roster before Game 3 when Walker Buehler is activated from the paternity list." That would put Buehler back in uniform when the series shifts to Petco Park, assuming San Diego gets that far.

The timing adds a layer of stakes: the Padres have to win Sunday's Game 2 just to keep the series even. Teams that drop the first two games of a Division Series on the road have rallied to win just three times in 36 tries under the current format, and a Game 2 loss would leave San Diego needing a sweep of Games 3 and 4 at home to survive.

San Diego's series isn't the only Division Series hanging in the balance Sunday — a separate account from another newsroom tracks how the Dodgers seized Game 1 control of their own NLDS matchup with Atlanta, underscoring just how unforgiving an 0-1 hole is in a best-of-five format.

Buehler's season has been one of the Padres' more unlikely bright spots. The 31-year-old signed a one-year deal with San Diego last offseason after eight seasons with the rival Dodgers, arriving on the heels of a second Tommy John surgery and a rough stretch that had pushed his strikeout rate into the bottom tenth of the league. He finished the regular season at 6-5 with a 5.18 ERA, but turned a corner down the stretch — a 2.92 ERA over his final seven starts — as the Padres leaned on him amid injuries to Nick Pivetta, Joe Musgrove, Matt Waldron, Germán Márquez and Yu Darvish.

"It always feels good when Michael's on the mound," Padres manager Craig Stammen said of Game 2 starter Michael King, as his club tries to even the series without Buehler available.

Neither the Padres nor Buehler had publicly detailed the birth as of Sunday morning; MLB's paternity list exists precisely so players can step away for a birth without a club having to lose the roster spot long-term, and San Diego's swap with Vásquez is the standard mechanism for covering it in-season.

What's next is straightforward on paper, complicated in practice: San Diego and Milwaukee play Game 2 Sunday at 4 p.m. ET in Milwaukee, with Michael King facing Logan Henderson. If the Padres survive to Game 3, expect Buehler reinstated and Vásquez to come off the roster — exactly the swap MLB.com flagged before a pitch was even thrown Sunday.