Rays 3, Mariners 2: Elliot Johnson hit a walk-off single with one out in the 12th inning as Tampa Bay captured the series opener.
B.J. Upton went 3-for-5 with an RBI and Carlos Pena also collected three hits for the Rays, who lost Evan Longoria after three innings with a sore left knee.
Ben Zobrist drew a one-out walk from Brandon League (0-2) and Pena recorded his third hit before Johnson hit a line-drive single to left field to plate the winning run.
J.P. Howell (1-0) worked a scoreless top of the 12th for Tampa Bay, which has won eight of nine overall and improved to a league-best 9-1 at home.
Seattle grabbed a 1-0 lead in the top of the second when Miguel Olivo launched a 1-0 offering from Tampa Bay starter Jeremy Hellickson into the left-field seats with one out for his third homer of the season. The Rays answered in the bottom half as Sean Rodriguez plated Brandon Allen with a single.
Jesus Montero, who began the game as the designated hitter but came in to catch in the ninth when Olivo suffered a groin injury, put the Mariners ahead with a leadoff homer off Wade Davis in the 11th. But League was unable to preserve the lead in the bottom half, allowing a leadoff double by Luke Scott and a two-out RBI single by Upton.
GAME NOTEBOOK: Tampa Bay added potential offensive help Monday, signing veteran Hideki Matsui to a minor-league contract. The 37-year-old Matsui, who had 12 home runs and 71 RBIs with Oakland last season, will report to extended spring training in Port Charlotte on Wednesday. ... Longoria appeared to injure himself when he was thrown out attempting to steal second base. After sliding awkwardly and catching his foot on Seattle shortstop Brendan Ryan's cleat, he walked back to the dugout with a slight limp. ... League's blown save was his second in eight opportunities in 2012. ... Mariners starter Felix Hernandez struck out nine over eight innings. He has 76 strikeouts in 75 career innings against the Rays.