Magglio Ordonez homered and Brandon Inge hit a tying double in the eighth for the Tigers, who fought back from a 6-1 deficit after starter Dontrelle Willis walked seven in 3 1/3 innings.
Ordonez opened the 12th with a single off Manny Delcarmen (1-2) and went to third on a one-out single by Brennan Boesch off Scott Schoeneweis — his fourth hit of the game.
Ramirez came in to face Inge and walked him, loading the bases. Alex Avila pinch hit for Gerald Laird and struck out, but Santiago won it without taking a swing.
Jose Valverde (1-1) got the victory with an inning of scoreless relief.
The Tigers trailed 6-1 after five and were still down 6-4 entering the eighth, but Ordonez made it a one-run game with a long homer to left off Hideki Okajima.
Cabrera followed with a walk, Boesch singled and Inge tied the game with a double.
Detroit, though, couldn’t take the lead. Okajima struck out Laird with runners on second and third, and pinch-hitter Santiago lined out to third.
Jonathan Papelbon replaced Okajima and got Adam Everett to pop out on the first pitch.
The Red Sox had runners in scoring position in both the 10th and 11th, but Joel Zumaya got out of both jams.
Neither starter got a decision. Jon Lester allowed four runs on four hits and four walks in seven innings. He struck out 10.
Detroit’s late rally saved Willis from a loss after his worst start of the season. He gave up four runs and four hits.
Willis struck out two of Boston’s first four hitters in the third, but walked the other two. David Ortiz broke the scoreless tie with an RBI single, and after Willis walked Adrian Beltre to load the bases, J.D. Drew made it 3-0 with a ground-rule double to center.
Scott Sizemore started the Detroit third with a walk and scored on Everett’s double — the only hit off Lester in the first five innings — but Willis continued to struggle.
He left with two on in the fourth and Ortiz increased Boston’s lead to four runs with a two-out RBI single off Eddie Bonine.
Bill Hall made it 6-1 in the fifth with his second homer in two days, a two-run shot off Bonine.
Boesch’s two-run triple pulled the Tigers to 6-3 in the sixth. Inge made it a two-run game with a sacrifice fly.
Detroit LF Casper Wells made his major league debut, batting second. Wells, called up Friday, is scheduled to return to Triple-A Toledo on Sunday to make room for RHP Armando Galarraga. … Beltre is 8-for-10 in his career against Willis. … Boston’s Kevin Youkilis had a career-high five walks. … Tigers reliever Zach Miner sustained a partial tear of an elbow ligament while pitching in extended spring training and is expected to miss the rest of the season. … The game was delayed for a few moments in the top of the ninth after plate umpire Ron Kulpa was hit in the mask by Jeremy Hermida‘s foul ball on a 100-mph fastball from Zumaya. Kulpa stayed in the game after being examined by Tigers trainer Kevin Rand.