ST. PETERSBURG, Fla. -- Clutch hitting once again carried the San Francisco Giants in the late innings on Sunday as they rallied for four runs in the eighth in a 5-1 win over the Tampa Bay Rays at Tropicana Field.

The victory completed a three-game sweep and extended San Francisco's win streak to eight straight contests.

"Just getting big hits, timely hits," Giants manager Bruce Bochy said. "(Joe) Panik was huge. Their pitching did a great job, their starter did a great job like ours."

Tied in the eighth inning, the Giants (44-26) received RBI singles from Panik and Buster Posey and a two-run double from Conor Gillaspie. The Rays (31-36) have dropped four straight and saw their bullpen struggle again.

A day after winning Saturday's game with a three-run homer in the ninth, Panik broke another late-inning tie with an RBI single in the eighth to score Gregor Blanco. Reliever Xavier Cedeno (3-2) got only one out, giving up two singles and a walk as the Rays' bullpen continues to struggle in high-leverage situations.

Taylor Sturdevant came in and gave up another RBI single to Posey for a 3-1 lead, then a two-run double to Gillaspie.

The Rays got singles from Corey Dickerson and Desmond Jennings to lead off the ninth, but reliever Cory Gearrin recorded the last two outs with strikeouts to secure the win.

For six innings, the game was a pitchers' duel between Giants starter Jake Peavy and Rays hurler Jake Odorizzi, each holding the opponent to a single run on four hits. For the second contest in a row, the game would by decided by the bullpens.

"I tried to hold them to one run as long as I could," Odorizzi said. "We just didn't close, and that's going to happen from time to time."

The Rays went 0-for-11 with runners in scoring position, and finished the three-game series 0-for-20. Over the last five games, they're 4-for-49, which is an .082 average.

"That's baseball - it happens," said Steve Pearce, who went 0-for-4 with two strikeouts. "We have to find some way to get the job done, and right now we're not getting it done. We're going to put this series behind us. We won five series before this one, so chalk this one up and go on the road now."

The Rays scored early, getting a run in the bottom of the first when Logan Forsythe and Brad Miller singled, and Forsythe scored on an error by Peavy on a pickoff attempt to first. That said, the Rays had Miller at third with one out, got an extra out when the Giants dropped a foul pop and still couldn't bring him in, with Dickerson striking out with two on to end the inning.

The Rays also had runners on first and third with two outs in the second, but Miller grounded out to end the inning.

The Giants committed three errors and gave up four hits in the first three innings, but limited to the damage to a single run.

"To hold them to one run was really impressive, considering all that happened behind (Peavy)," Bochy said. "We made Jake work pretty hard the first three innings."

The Giants' lone run early came on a solo homer by Brandon Belt -- his 10th of the season -- off Odorizzi in the fourth inning to tie the game.

Gillaspie entered the game late for starting third baseman Matt Duffy, who went 2-for-3 on the day. Bochy said his Achilles tendon, which had bothered him in spring training, flared up after he stepped on a base awkwardly. He's day-to-day officially, and will be evaluated Monday in Pittsburgh.

NOTES: The Rays lost Saturday despite hitting four home runs -- since the start of last season, teams hitting four or more home runs have won 89.8 percent of the time. ... The Rays made history, according to Elias, as the first MLB team ever to have four infielders hit home runs from the first four spots in the batting order. It was also the first time in Rays history that four infielders homered in the same game. ... The Giants continue their road swing with a four-game series at the Pirates starting on Monday, while the Rays hit the road for a three-game series at Cleveland. ... Since May 11, Giants starting pitchers were 17-4 with a 2.21 ERA entering Sunday's game -- for the year, Giants starters have a 3.38 ERA, fourth-best in the National League behind the Cubs, Mets and Nationals.