OAKLAND -- A's right-hander Marco Estrada underwent an ablation procedure on his back Tuesday to try to reduce the pain he's been feeling. The 35-year-old was placed on the injured list last week with what the team called a lumbar strain.

Radiofrequency ablation is a nonsurgical, minimally invasive procedure, which uses heat to stop the transmission of pain to the brain. There is still no timetable for Estrada's return, but he will miss more than one start.

"It's going to be longer than a 10-day period," A's manager Bob Melvin confirmed Tuesday. "It's still kind of undetermined as it goes with him."

Estrada has dealt with back problems for much of his career, including last season with the Blue Jays. It recently flared up again, causing a dip in velocity and trouble locating his pitches. 

"He's dealt with this before," Melvin said. "So maybe some other guys you might say it's going to be a longer period of time, but it just depends on how he feels after this procedure."

Oakland signed Estrada to a one-year, $4 million contract this offseason. In five starts this year, he is 0-2 with a 6.85 ERA and 1.31 WHIP.

Chris Bassitt, who replaced Estrada in the rotation, made his first start of the season Monday night and tossed five scoreless innings in a 6-1 win over the Texas Rangers.


"We'll let him start again after that one," Melvin said.

Melvin also expects left-hander Brett Anderson to make his next start, despite leaving his last outing with a sprained ankle.

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"I still think Brett's going to be able to pitch," he said. "He's going to have an extra day because of the off day as well, so I think we'll be in pretty good shape there."

Frankie Montas takes the hill Tuesday night as the A's try to make it two in a row over the Rangers.