SAN FRANCISCO -- With Buster Posey still nursing a left thumb injury, the Giants supplemented their coverage behind the plate by recalling catcher Chadwick Tromp from Triple-A Sacramento ahead of Monday afternoon’s 5-3 series-opening loss to the Cardinals at Oracle Park.

To clear a spot for Tromp on the 26-man roster, the Giants placed rookie left-hander Sammy Long on the 10-day injured list with a lower back strain.

Posey suffered a left thumb contusion after taking a foul tip off his glove hand in the sixth inning of the Giants’ win over the D-backs at Chase Field on Sunday. X-rays came back negative, but Posey is still dealing with soreness and was scheduled to undergo further evaluation from team orthopedist Dr. Kenneth Akizuki on Monday.

Are the Giants still optimistic that Posey will be able to avoid a stint on the IL?

“I think he’s on the roster today, and that’s a good start,” manager Gabe Kapler said. “I’ll chat with him and see how he’s doing after.”

Backup Curt Casali batted eighth against Cardinals left-hander Kwang Hyun Kim on Monday and caught Kevin Gausman, who took a no-hitter into the seventh inning. Tromp entered as a defensive replacement in the ninth inning.

Kapler said Long’s back tightened up after his last start against the D-backs on Saturday, when he surrendered four runs on seven hits over four innings to bump his ERA to 5.63 over five Major League appearances this year. Long had been lined up to pitch on Saturday against the Nationals, but the Giants won’t necessarily need a replacement, as they’ll have the option to stick with a four-man rotation until the All-Star break.

With an off-day on Thursday, the Giants could bring back Anthony DeSclafani on normal rest on Friday, deploy Gausman on Saturday and have Johnny Cueto pitch the first-half finale on Sunday.

“Yeah, that’s a possibility,” Kapler said. “We’ve got other things to work through and other conversations to have. We kind of just made the determination that Sammy is going to be on the IL, so we’re probably going to have discussions throughout the day about how to fill that rotation spot.”

Estrada starts in left
With Mike Yastrzemski receiving a scheduled day off from the starting lineup, Thairo Estrada made his first start in left field for the Giants on Monday and got San Francisco's defensive highlight reel going with a leaping catch in the first inning to rob Nolan Arenado of extra bases. Estrada, 25, is primarily a middle infielder, but he made four appearances in the outfield for the Yankees in 2019 and has also played there in the Minors.

“I think it’s similar to the way we view [Mauricio] Dubón,” Kapler said. “We like the fact that he can move around the diamond. We’re very comfortable with him at second, short and third. This is going to be his first start [in left field], but he’s made starts in Triple-A. We have him ready for this opportunity. It’s as much as about getting as many righty bats into the lineup as possible, knowing that Estrada can hold down the fort in left.”