ST. LOUIS -- Willson Contreras belted two solo homers Friday night in the Chicago Cubs' one-run win.

Like most catchers, though, Contreras' favorite moment came on a play that potentially prevented a run.

With the St. Louis Cardinals mounting a rally in the bottom of the seventh inning after consecutive walks put the potential tying runs on base, Contreras cut it off with a pickoff of former teammate Dexter Fowler at first for the third out.

That play and his first multi-homer game of his career more than offset his bizarre throwing error with two outs in the ninth that injected some last-minute spice into Chicago's 3-2 victory at sold-out Busch Stadium.

"Willson at the plate really caught well. He blocked a ton of balls in the dirt, and he had that 503 mile-per-hour throw to first for the final out," Cubs manager Joe Maddon grinned.

Closer Wade Davis appeared to have fanned Kolten Wong with a 3-2 knuckle-curve in the dirt for the 27th out. But Contreras' throw to first soared off the outstretched glove of Anthony Rizzo and down the right-field line as Randal Grichuk scored from second.

The two-base error gave Matt Adams, 6-for-16 as a pinch-hitter this year, a chance to deliver a game-tying or winning hit. However, Davis dispatched him on three pitches for his eighth save in as many chances as Chicago (18-17) won for just the second time in seven games.

It preserved a win for Eddie Butler, making his first big league start of the year. Looking nothing like the pitcher who was 6-16 while pitching parts of the last three years for Colorado, Butler checked St. Louis (19-15) on two hits in six shutout innings, walking three and fanning five.

"He was really good, had really good stuff," Cubs manager Joe Maddon said of Butler. "This was like a mirror image of what he was doing in Triple-A. He’s a strike-thrower."

Butler's batterymate was a strike-thrower two innings before his shocking error. After Hector Rondon threw ball two to Tommy Pham, Contreras rifled a strike to Rizzo and Fowler was out by several feet, silencing the Cardinals' portion of the audience of 47,601.

"Dexter was really far off the bag," Contreras said. "The timing was good between Anthony and me, and he put a good tag on him."

Earlier, Contreras presented Butler a two-run cushion with two authoritative swings of the bat. He ripped a one-out homer off Mike Leake (4-2) in the second that went 391 feet to the seats in right field, exiting the bat at 109.5 mph.

Two innings later, Contreras powdered a 418-foot shot to left center. Fowler gave the ball a cursory look and stopped trotting toward the wall about five steps after he started, knowing it was bleacher-bound.

That gave Contreras four homers for the year -- three in St. Louis.

"I don't know what's going on in this ballpark," he said, "but I'm seeing the ball well here."

Tommy La Stella accounted for Chicago's other run with a one-out solo shot in the seventh. La Stella was a second-inning replacement for right fielder Jon Jay, who departed with back spasms. Jay filled in for Kris Bryant, who was scratched five minutes before game time with a stomach bug.

Against a short-handed Cubs lineup, Leake pitched well enough to win most games. He gave up just five hits and three walks in six innings, fanning five. But his teammates were baffled by Butler, who touched 97 mph with his fastball and looked nothing like a guy who had a 6.50 ERA in 36 prior appearances with the Rockies.

"You're just going to have those games," Cardinals manager Mike Matheny said. "It seems like we have them often against young pitchers we haven't seen that much."

Grichuk cracked his fourth homer of the season in the seventh for St. Louis, which scored 45 runs in its previous six games, all wins.

NOTES: Chicago SS Addison Russell (right shoulder) didn't start for the second straight game, although he drew a pinch-hit walk in the eighth inning. ... The Cubs recalled RHP Eddie Butler from Triple-A Iowa to start, optioning RHP Justin Grimm to Iowa. ... St. Louis CF Dexter Fowler (right shoulder) was back in the starting lineup after not starting on all six games of the team's road trip to Atlanta and Miami. ... Cardinals RF Stephen Piscotty (right hamstring) anticipates being ready to play after his stint on the 10-day DL ends Monday.