ST. LOUIS — There were tough at-bats, relentless comebacks and mostly strong defense — only it was the St. Louis Cardinals, not the Diamondbacks, who were playing that brand of baseball.

The Diamondbacks were beaten, 4-3, on May 25, as the Cardinals completed a three-game sweep at Busch Stadium. The loss dropped the Diamondbacks under .500 for the first time since the second week of the season.

The Diamondbacks allowed multiple leads to get away from them. They were ahead, 2-0, after the top of the first, but the Cardinals drew even with a run in the bottom of the first and another in the third against right-hander Brandon Pfaadt.

The Diamondbacks moved back in front in the sixth on Pavin Smith’s RBI single, but the Cardinals answered in the bottom of the inning, then moved in front for good in the seventh on Victor Scott II’s RBI single.

Just as they did in the previous two losses in this series, the Diamondbacks made things interesting in the ninth. They put runners on first and second with no outs but failed to score. Corbin Carroll struck out, Ketel Marte popped out and Lourdes Gurriel Jr. struck out against Cardinals reliever Phil Maton.

ST. LOUIS — Right-hander Brandon Pfaadt is through five solid innings, and the Arizona Diamondbacks and St. Louis Cardinals are tied at 2 after five innings on May 25, at Busch Stadium.

Pfaadt allowed a run in the first on Ivan Herrera’s RBI-single to center and another in the third on Masyn Winn’s solo homer. He has given up some hard contact but no other damage, walking none and striking out five.

The Diamondbacks scored a pair of runs on Eugenio Suarez’s bloop single to right in the top of the first inning. Ketel Marte (single) and Josh Naylor (double) set the table for Suarez, who dumped a two-strike pitch from Cardinals right-hander Sonny Gray into no-man’s land in shallow right field.

The Diamondbacks are looking to avoid a three-game sweep and return home from their road trip with a 2-4 mark. A loss would mean a 1-5 record on a trip that began with a series loss at Dodger Stadium.

Left-hander Eduardo Rodriguez threw three innings and 55 pitches in a simulated game on May 24, manager Torey Lovullo said.

It is not clear what will come next for Rodriguez, who is on the injured list with left shoulder inflammation, but Lovullo made it sound like when Rodriguez returns, he will reclaim his rotation spot despite his struggles before the injury.

“I feel like he deserves that,” Lovullo said. “He was one of our guys to start the season and he got hurt. In my opinion, he deserves to fall back into the rotation.”

Rodriguez was serviceable from a results perspective early in the season — he logged a 4.40 ERA through his first five starts — and might have actually been pitching better than his numbers showed.

But things backed up for him in a big way after that. Over his four starts before landing on the IL, he gave up 24 runs (21 earned) in 16 innings, allowing 28 hits (including five homers) while issuing 11 walks.

His replacement in the rotation, right-hander Ryne Nelson, allowed one run in five innings in a start at Dodger Stadium last week.

Diamondbacks at Cardinals, 11:15 a.m., Cox, Ch. 34

Diamondbacks RHP Brandon Pfaadt (7-3, 3.81) vs. Cardinals RHP Sonny Gray (5-1, 4.02).

At Busch Stadium: Pfaadt gave up three runs in six innings in a win at Dodger Stadium last week, the second time he has beaten the Dodgers this month. … Still, he is in a bit of an uneven stretch; over his past four starts, he has allowed 14 runs (13 earned) in 21 innings. … He has faced the Cardinals twice in his career, both starts coming last year. He allowed eight runs in 11 1/3 innings in those outings. … Gray is coming off a dominant outing against the Detroit Tigers, striking 10 over six scoreless innings. He gave up just three hits and walked one. … He has had three such dominant, scoreless performances this year but has yet to string together multiple impressive outings. … He has faced the Diamondbacks only once in his career, giving up four runs (two earned) in 6 1/3 innings in a start in 2015.

Coming up

May 26: At Chase Field, 5:10 p.m., Diamondbacks RHP Ryne Nelson (1-1, 4.60) vs. Pirates LHP Andrew Heaney (3-3, 2.91).

May 27: At Chase Field, 6:40 p.m., Diamondbacks RHP Corbin Burnes (3-2, 2.73) vs. Pirates RHP Mike Burrows (0-1, 7.20).

May 28: At Chase Field, 12:40 p.m., Diamondbacks RHP Zac Gallen (3-6, 5.25) vs. Pirates RHP Paul Skenes (3-5, 2.36).