PHOENIX -- In the midst of the Albert Pujols party, the bullpen continued to struggle.

After his electric Saturday night in the desert, Pujols came off the bench to pinch-hit Sunday in the seventh inning and promptly delivered a base hit to the roar of both fanbases. It led to the Cardinals reclaiming a lead they kept the rest of the way in their 6-4 win to sweep the D-backs in the three-game series at Chase Field.

“It was a frustrating three games,” Arizona manager Torey Lovullo said afterward. “We’re playing good baseball.”

After a shaky first inning, D-backs starter Merrill Kelly settled in. The July NL Pitcher of the Month who entered the matinée with a 4-0 record and 1.64 ERA in his past nine starts, allowed three runs on seven hits with three walks and six strikeouts in his six innings of work.

But after left-hander Joe Mantiply came on to pitch in the seventh, the Cardinals called on the right-handed Pujols off the bench with one on and one out.

Pujols, who had four hits with two home runs Saturday and passed Stan Musial for second on the AL/NL total bases list, drew a huge ovation from the crowd of 25,064 as he walked up to the plate. His single up the middle sent Lars Nootbaar to second, and Pujols was promptly lifted for pinch-runner Tommy Edman.

Lovullo then replaced Mantiply with Kevin Ginkel to face former Arizona slugger and current NL MVP candidate Paul Goldschmidt. Ginkel’s first pitch drilled Goldschmidt on his elbow guard to load the bases with only one out.

Designated hitter Nolan Arenado came to the plate to chants of “Let’s go Cardinals” from the charged-up St. Louis faithful in the Phoenix crowd and delivered a two-strike RBI single to right to bring home Nootbaar and Edman and put the Cardinals back on top.

The D-backs had led 4-3 through six innings by the time Kelly exited.

In Arizona’s previous six games coming in, the D-backs relievers had been reached for 16 earned runs on 24 hits in 17 innings, recording a combined ERA of 8.47. On Sunday, the ‘pen combined for three runs on five hits through three innings pitched.

It has all come during a taxing stretch that saw the D-backs play 17 games in 17 days through Sunday.

“Not putting the ball in play, a lot of walks,” Lovullo said of what he’s seeing from the relievers. “That’s a recipe for some tough outings. I just want our guys to put the ball in play and believe in their stuff.”

Kelly has gone five starts without recording a decision. Over that time, he’s thrown 32 innings while allowing eight earned runs on 25 hits and 11 walks and striking out 32 for a 2.25 ERA.

Kelly’s last decision was in a 7-0 win over the Giants on July 25 when he pitched eight scoreless innings.

“The only reason it frustrates me is that we as a team don’t get the win,” Kelly said. “Some days I can pitch like [garbage] and get the win, and some days I pitch great in a loss. The win stat for a starting pitcher is always a little weird.”

A bright spot for the D-backs continues to be the emergence of outfielder Jake McCarthy. After going 1-for-2 with an RBI, two walks and a run scored Sunday, the 25-year-old has hit safely in 11 of his past 13 games, with 10 RBIs over that span.

Arizona has an off-day Monday and opens a quick two-game series in Kansas City from Tuesday to Wednesday. Right-hander Zach Davies (2-4, 3.99) is scheduled to take the mound.

Of the nine teams the D-backs will face over their final 41 games, six are over .500, including two division leaders (Dodgers, Astros).

A day after the future Hall of Famer wowed the big crowd, Pujols was honored by the D-backs prior to the game Sunday. He was making his last career visit to Phoenix, as was future Hall of Fame teammate Yadier Molina.

Molina was put on the restricted list while in Phoenix for what Cardinals manager Oliver Marmol called “business matters,” and the 10-time All-Star missed the final two games of the series. The D-backs honored Pujols and Molina before the game, with right-hander Adam Wainwright standing in for Molina. The two are the all-time winningest starting battery in AL/NL history