The right-hander, who lost his spot in the starting rotation last season after helping the Rays win the AL pennant in 2008, pitched four scoreless innings in Thursday's 4-1 split-squad victory over the Toronto Blue Jays.
Combined with a 16-15 split-squad victory over the Pittsburgh Pirates in Bradenton, the Rays have won a club-record nine straight exhibitions since losing their spring opener to the Baltimore Orioles.
Rebounding from a poor outing in his spring debut, Sonnanstine allowed one hit and one walk while striking out three. He worked one inning against Boston last Saturday, giving up two runs, one hit and walking three with no strikeouts.
"I felt like my command was very good today. I moved the ball in and out and was hitting spots. ... That's one of the biggest things to me having success," Sonnanstine said after the 49-pitch outing.
"He just looked like himself today," manager Joe Maddon said. "I really expected him to be a lot better."
Sonnanstine went 13-9 with a 4.38 ERA in 32 starts while helping Tampa Bay reach the World Series two seasons ago.
He began 2009 at the No. 4 starter, but was demoted to Triple-A Durham in late June after going 6-7 with a 6.61 ERA in 15 starts. At the time, he had the highest ERA in the majors and opponents' .305 batting average was the second-highest in the AL.
Sonnanstine, who turns 27 next week, said the biggest difference between Thursday and last Saturday's outing was his ability to calm down.
"I was really excited to get out there for the first time, and I think that worked against me a little bit. Today I did a good job of managing my excitement," he said.
John Jaso hit a solo homer off Shawn Camp with one out in the fifth. Jason Bartlett and Evan Longoria had RBI singles later in the inning, and Chris Richard added a run-scoring double in the seventh for the Rays.
Toronto starter Shaun Marcum gave up one hit, walked none and struck out two in three scoreless innings.
Cuban 1B-OF Leslie Anderson has agreed in principle to a contract with the Rays, who said there are still some details to worked out. ... Camp, a former Rays reliever, allowed three runs and six hits in two innings. ... Tampa Bay reassigned SS Tim Beckham and C Nevin Ashley to minor league camp. LHP Jake McGee was optioned to the minors, however the team did not say to which affiliate. ... C Dioner Navarro injured his left thumb when he was struck by a pick-off throw to first base during the split-squad game against the Pirates in Bradenton. X-rays were inconclusive. He will rest the thumb and be revaluated in a couple of days.