Padres pregame: Matt Waldron called up to start opener; Matt Carpenter back in starting lineup

The Padres have called up right-hander Matt Waldron from Triple-A El Paso to start Game 1 of Saturday’s doubleheader, a bullpen game that will leave Yu Darvish as the backstop for the nightcap.

Waldron last started for El Paso on Tuesday, throwing 28 pitches (21 strikes) over two shutout innings. With Waldron on three days rest, it’s unlikely he approaches his season high (six innings), especially because he’s not the traditional knuckleballer featuring the pitch enough to reduce the wear and tear on his arm (Waldron threw his floater 21 percent of the time in debut in June).

Seth Lugo saved the Padres’ pen in Friday’s 4-0 win, throwing six shutout innings ahead of Scott Barlow, Robert Suarez and Josh Hader closing out the game with a frame apiece. With Pedro Avila throwing four innings to close Thursday’s game, no reliever is entering the doubleheader having already pitched in back-to-back games.

Hader will only be available for one of today’s games, which will have a monumental impact on the NL wild-card race if either team sweeps.

Consider Darvish a backstop if the Padres wind up throwing everyone they can in the opener.

Darvish leads the team with 5.78 innings per start this year and his 127 1/3 innings are just behind Blake Snell (136) despite having three fewer starts.

Darvish has also gone at least six innings in four straight games (2.08 ERA) and six of his last seven (2.98 ERA).

In other words, Darvish (8-8, 4.24 ERA) is the Padres’ best bet to provide length, even if his ERA is up by more than a run from where he finished last year (3.10).

He is 1-0 with a 1.69 ERA, eight strikeouts and nine walks in two starts this year against the Diamondbacks and has a 3.36 ERA in 17 career starts against Arizona.

Waldron is making his second big-league start, having allowed two runs on two four hits and a walk to the Nationals on June 24.

The 26-year-old has a 7.28 ERA in 85 1/3 innings this year in the Pacific Coast League, where the circuit-wide ERA is 5.86.

Waldron walked through the clubhouse doors at 9:54 a.m.

The lineup behind him will see Matt Carpenter starting for the first time since July 23 in Detroit and at first base in a starting lineup for the first time since May 12 at Dodger Stadium. Carpenter was a defensive replacement at first on Friday for Garrett Cooper, who jammed his wrist.

Manny Machado is DHIng for a third straight game as the Padres manage his sore elbow. Machado is expected to return to the field for the nightcap.

As for the Diamondbacks, they are saving their bullpen game for the nightcap (starter TBA) and going with right-hander Merrill Kelly (9-5, 3.05 ERA) in Game 1.

The longtime D-back is 8-3 with a 2.91 ERA in 14 career starts against the Padres, but he allowed four runs in five innings in his lone start this year against San Diego, back in April. Arizona has lost his last three starts despite Kelly striking out 22 against four walks over 18 innings (2.00 ERA).