CHICAGO -- Three pitches after giving up a home run to Christian Yelich on Saturday, Cubs lefty Brad Wieck buckled on his follow through and gave his right leg a shake on the mound at Wrigley Field. One day later, Chicago was forced to adjust its bullpen.

Prior to Sunday's series finale against the Brewers, the Cubs placed Wieck on the 10-day injured list with a strained right hamstring and called veteran righty Ryan Tepera up from the alternate training site in South Bend, Ind. There is no timetable for return for Wieck, who will head to South Bend to begin his rehab.

"We're going to get him in South Bend," Cubs manager David Ross said on Sunday morning. "It's hard to say with the hammy -- just make sure he's healthy first and just continue to get him back to full strength."

Wieck pitched in the sixth inning of Saturday's 8-3 loss to the Brewers and allowed two runs (both via Yelich's blast) and finished with one walk and two strikeouts in the 20-pitch showing. Wieck's average fastball velocity was down to 90.4 mph (per Statcast), compared to 93.7 mph in 2019.

"That's something that we're paying attention to," Ross said of Wieck's fastball velocity on Saturday. "He's been about 89-91 [mph] throughout this mini camp. He is coming back from some medical stuff, so we've just got to continue to monitor that and continue to communicate with him."

Ross was not referring to the hamstring issue, but rather that Wieck underwent a heart procedure in February. The three-month shutdown period afforded him time to recover and build back up for Opening Day."

Ross has "trust" in Tepera
When the Cubs optioned Tepera to the South Bend site on Thursday, president of baseball operations Theo Epstein emphasized that the move was based on preparation and not ability. A few procedural delays during Summer Camp disrupted the reliever's throwing program.

"It's not a matter of him not having the talent to help us," Epstein said Thursday, "because we think he certainly does and is going to play a large role and help us. He was just a little bit delayed. ... I don¡¯t want anyone to read in any more than that into his option."

The 32-year-old Tepera -- signed to a Major League deal over the offseason -- has a 3.64 ERA over the past five years in the big leagues with the Blue Jays. For his career, the sinkerballer has relatively even splits against righties (.220 average and a .645 OPS) and lefties (.220 average and a .754 OPS).

"I told him before I sent him down, I said, 'I trust you,'" Ross said. "He's a guy who's battle-tested and you love his attitude. He continues to get locked in and sharpen."

Worth noting
? In the second inning of Saturday's loss, Brewers outfielder Lorenzo Cain was caught in a rundown between second and third base on a grounder to shortstop Javier B¨¢ez off Ben Gamel's bat. Cain retreated to second safely and Gamel reached first in a costly botched defensive play.

"We've got to handle that better, no doubt about that," Ross said. "I think everybody, to a man, would admit that. We've got to handle that situation better. Every out matters. Every pitch matters."

? Through the first two games of the season, five of the six runs scored by the Cubs have come via homers by Ian Happ, Anthony Rizzo and Kyle Schwarber. Ross said he's "all for the homer," but knows the lineup needs to keep working toward manufacturing runs.

"Our guys have had great at-bats, in my opinion," Ross said. "Yeah, we definitely need to stay up the middle, the other way, just in general in our approach. But, these guys play the game pretty well, and that game inside the game inside the box, they've been doing a pretty good job."

? Ross said that utility man Hernán Pérez will be a part of the three-man taxi squad for the Cubs' four-game road trip to Cincinnati, beginning Monday. The rest of the additional traveling group is still being determined.