ST. PETERSBURG, Fla. -- Jeremy Hellickson is emerging as a rookie of the year candidate with the potential to be much more than that.
"He's definitely a candidate," Rays manager Joe Maddon said. "I really believe as he gains more experience, you're going to see him get even better. He has not been as sharp with his fastball command as he can. Once that arrives, he's really going to take off."
Hellickson (6-3) scattered three hits, walked two and had six strikeouts. The right-hander has won five of his last six starts.
"Fastball command was a little shaky early, but the curveball and change up kept me in the ballgame," Hellickson said.
Jaso hit a two-run homer off Justin Masterson (5-3) as Tampa Bay went ahead 4-0 in the fourth. Ben Zobrist had an RBI grounder and Sam Fuld hit a run-scoring infield single in a three-run fifth that extended the Rays' lead to 7-0.
Masterson, 1-6 in 11 career games against Tampa Bay, allowed seven runs, eight hits and five walks in five innings. He was winless in his five previous starts -- including two losses -- despite a 2.80 ERA over the stretch.
The AL Central-leading Indians are 11-11 since May 4. Cleveland also was blanked 5-0 in Friday's series opener.
"Certainly not the way you want to start a road trip, especially being shut out two of three games," Cleveland manager Manny Acta said. "Justin had a rough day. Really struggled with his command. You could tell from the get-go."
Johnny Damon had an RBI single during a two-run third that put the Rays up 2-0. The other run scored when catcher Lou Marson was charged with a passed ball that allowed Evan Longoria to score from third.
Longoria, batting leadoff for the second straight game, had two hits and walked twice. He had two hits and a walk in Saturday's 7-3 loss to the Indians.
Maddon said he has not decided if Longoria will hit first again Monday night against Texas.
Tampa Bay's Matt Joyce, who started the day leading the majors with a .374 batting average, went hitless in four at-bats. His dropped his average to .365.
Hellickson worked out of a two-on, one-out jam in the first by getting a double-play grounder from Travis Buck. The right-hander struck out Grady Sizemore with two runners on and two outs to end the fourth.
"We just couldn't make the adjustments offensively against Hellickson," Acta said. "He had a very good change up as usual. Mixed his pitches very well."
Sizemore was the designated hitter for the third straight game and struck out in all four plate appearances. He is hitless in 12 at-bats, including seven strikeouts, since returning from a bruised right kneecap on Friday.
"Had a rough day at the plate," Acta said.
The Indians are still planning to have Sizemore play the field once during a three-game series that starts Monday night at Toronto.
Rays RHP Jeff Niemann (strained lower back) will throw around 45 pitches in a simulated game on Monday. The best-case scenario for Niemann to rejoin the team is in a couple of weeks. ... Tampa Bay minor league RHP Alex Cobb could be recalled from Triple-A Durham to start Tuesday night's game against Texas. That rotation spot is currently held by RHP Andy Sonnanstine, who has been filling in for Niemann. ... Damon's grounder to first that was scored an error in the ninth inning of Saturday's game was changed to an RBI single. ... The Rays issued a statement through spokesman Rick Vaughn one day after singer Avril Lavigne used an expletive several times following technical problems during a postgame concert. "The Rays demand profanity-free performances from all of our concert performers and we are extremely disappointed by the language used in last night's show. It is not consistent with the family-friendly atmosphere that Tropicana Field is known for."