The right-hander is helping the Kansas City Royals' staff get off to a good one in 2013.
Shields faces his former Rays teammates for the first time in Tuesday night's series opener at Kauffman Stadium.
Drafted by the Rays out of high school in 2000, Shields (1-2, 3.09 ERA) came up through the organization and went 87-73 with a 3.89 ERA in seven seasons. An All-Star in 2011 when he finished third in the AL Cy Young voting, the right-hander is the Rays' all-time leader in wins, games started (217), complete games (19), innings (1,454 2-3) and strikeouts (1,250).
Shields, though, now wears a Royals uniform after coming over with Wade Davis and shortstop Elliot Johnson in the December deal that Kansas City (13-10) made to bolster a staff that was 12th in the AL last season with a 5.01 ERA. That group has a 3.64 ERA this year despite a second consecutive rough outing from Davis in Monday's 9-0 loss to Cleveland.
Davis hopes to face the Rays (12-13) when the Royals play in St. Petersburg in June, but Shields gets his chance on Tuesday.
"It's kind of understandable that it's going to feel a little different," he told MLB.com. "It'll be exciting. It'll be fun."
It would be an even more enjoyable experience for Shields if he's on his game. The right-hander was unhittable to end his last outing, retiring the last 10 he faced in Thursday's 8-3, 10-inning victory at Detroit.
"The deeper he gets in those situations, the tougher he gets," manager Ned Yost told the Royals' official website.
Rays designated hitter Luke Scott has been a tough out for Shields, going 12 for 37 with a homer and four doubles, and he could make his season debut on Tuesday. He's been out with a strained right calf.
Scheduled starter Alex Cobb (3-1, 1.82) could be throwing to Jose Molina, who missed Sunday's 8-3 road win over the Chicago White Sox after getting hit above the knee by a pitch in the previous game.
Cobb will try to match a career high by winning a third consecutive start after striking out a season-best seven and finishing two outs shy of a complete game in Wednesday's 3-0 victory over the New York Yankees.
"I knew throwing out my first bullpen (session) that I was going to have good fastball location," Cobb told the Rays' official website. " When you have that mindset going into the first couple of innings, you get in kind of a groove and things just start to work out for you."
The right-hander is 1-1 with a 4.80 ERA in two starts against the Royals, both in Kansas City.
Cobb will face a Kansas City team that just fell out of the AL Central lead with its second straight loss.
"We had an off-day," said third baseman Mike Moustakas, who had one of the team's season-low three hits.
Alex Gordon went 0 for 4 for a second straight game and Alcides Escobar's team-best nine-game hitting streak ended. However, the Royals' 1-2 hitters were a combined 17 for 43 (.395) with seven extra-base hits off Rays pitching - including 6 for 7 off Cobb - last season to help Kansas City win four of six matchups, including all three at Kauffman Stadium.
The Royals have won seven of 10 at home in this series.