INGLEWOOD, Calif. — Las Vegas Raiders quarterback Aidan O’Connell suffered a broken thumb on his right (throwing) hand in the first quarter of Sunday’s game against the Los Angeles Rams, a source told ESPN’s Adam Schefter.

O’Connell will undergo further testing on Monday to determine how long he will be out, the source said.

Gardner Minshew, who was substituted for O’Connell last week, replaced O’Connell.

But because the Raiders don’t have a third emergency quarterback on the roster – receiver Jakobi Meyers was named as one but is missing his second straight game with an ankle injury – O’Connell’s return remained in doubt if Minshew was sidelined.

O’Connell appeared to clumsily slap his hand on the outstretched hand of rushing Rams safety Kam Curl on a deep throw. O’Connell, whose thumb was badly injured after returning from the locker room, completed 6 of 10 passes for 52 yards against the Rams. According to ESPN Research, he was pressured on five of his 10 dropbacks (50%) and was 2 of 5 for 19 yards when pressured.

Minshew, who signed a two-year free agent contract with $15 million guaranteed, won a tough training camp battle with O’Connell. Minshew completed a career-high 70.7% of his passes for 1,014 yards and four touchdowns, but was also picked off five times.

In his final game before being benched, Minshew threw a 100-yard pick-six against the Denver Broncos in Week 5, turning a potential 17-3 Raiders lead into a 10-10 game an eventual 34:18 defeat. Minshew had a career-low 40.2 QBR at the time of his benching.

Against the Rams, Minshew was 8 of 16 for 90 yards in the first half, with an interception and a lost fumble that was returned for a touchdown.