Brayan Bello delivers a pitch in his first career start for the Red Sox on Wednesday night against the Tampa Bay Rays at Fenway Park in Boston. Mary Schwalm/Associated Press

BOSTON — Corey Kluber worked six scoreless innings and the Tampa Bay Rays beat the Red Sox 7-1 on Wednesday night in the major league debut of Brayan Bello, the top pitching prospect in Boston’s system.

With a fastball topping out at 97 mph, the 23-year-old Bello (0-1) worked four up-and-down innings, allowing four runs on six hits with three walks and four strikeouts. The right-hander finished his 79-pitch outing by retiring two batters after Josh Lowe’s one-out double.

Randy Arozarena had a two-out, two-run double in the third against Bello, and Kevin Kiermaier had another run-scoring double to make it 4-0. Arozarena added a solo homer in the ninth off Tyler Danish.

Kluber (4-5) allowed three hits with no walks and five strikeouts.

Yandy Diaz doubled with one out in the first for the Rays and scored on Wander Franco’s single.

Tampa Bay extended its lead to 6-1 in the sixth against Hirokazu Sawamura on Lowe’s run-scoring double and a bases-loaded walk by Ji-Man Choi.

J.D. Martinez had an RBI single for Boston in the eighth.

NOTES: Boston LHP Chris Sale, out all season with a stress fracture in his right rib cage, made what could be his last rehab start, allowing one run on three hits and five walks with five strikeouts in 3 2/3 innings for Triple-A Worcester. … 3B Rafael Devers was out of the lineup with a sore back and a sore right hamstring. … CF Kiké Hernández, out since June 8 with a right hip flexor strain, is expected to start a rehab assignment on Friday. … LHP Josh Taylor, out all season with a low back strain, also made a rehab appearance for Worcester, striking out three in one inning. … LHP Rich Hill, sidelined with a left knee sprain, threw from flat ground. … RHPs Nathan Eovaldi, out since June 9 with low back inflammation, and Garrett Whitlock, out since June 9 with right hip inflammation, could start rehab assignments soon, Manager Alex Cora said.