The Angels have lost 13 of their last 18 games and are coming off a four-game sweep at the hands of the Rays, including an 8-3 loss on Sunday.
The Halos are in third place in the American League West and have fallen nine games behind the first-place Rangers. They are 4 1/2 games back in the AL Wild Card race and have three teams in front of them.
The Red Sox are in fourth place in the AL East with a 59-63 record, 13 1/2 games behind the division-leading Yankees after Sunday night's 4-1 loss in New York, and are 7 1/2 games back in the AL Wild Card race.
Right-hander Ervin Santana, who will start on Tuesday for the Angels, has struggled through a hard-to-explain season with a 6-10 record and a 5.59 ERA but is coming off one of his best outings of the year.
In his 23rd start of the season, on Wednesday against the Indians, Santana worked seven strong innings, giving up four hits and one run in an 8-4 victory.
"I know that I hadn't been pitching good, but I was just doing my best, and I just think positive every time," Santana said after the game. "The last few outings I had been getting better, and then tonight, even better."
Santana has no doubt that he is the same pitcher who compiled an 87-67 record in seven seasons in the Majors before this year.
"I don't have the good results sometimes, but I know I'm a good pitcher and I know I can do better than that," the 29-year-old Santana said of his 2012 results.
Angels manager Mike Scioscia is cautiously optimistic about Santana after the righty's last outing.
"He's closer," Scioscia said. "His breaking ball is more consistent, but maybe not quite where we've seen it before. I think that he's much closer. We're obviously happy with the strides he's made, and he's pitching at the level that we need. But there's still more in Ervin, and hopefully we're going to be able to grow with it."
Scioscia believes the Angels are still solidly in the postseason chase.
"I don't want to be redundant, but the season's still in front of us," Scioscia said. "We're going to have our opportunities if we get our team where we need it to be, and that's what we need to focus on."
Rookie sensation Mike Trout is also optimistic.
"It's baseball," Trout said on Sunday. "Just come out Tuesday against Boston and turn the page. The last couple of weeks have been tough, but you just have to stay positive."
Santana's counterpart, Red Sox righty Aaron Cook, is 3-6 with a 4.58 ERA in 10 starts.
Cook had it all working early in his start on Wednesday, no-hitting the Orioles through 5 1/3 innings before grabbing a potential double-play comebacker and throwing it into center field. The miscue ultimately led to five runs.
Cook threw 55 pitches and hardly broke a sweat in the first five innings, but from the moment the no-hitter ended with a single by J.J. Hardy, everything fell apart, and the reeling Red Sox went on to lose, 5-3.
"When you get the ground ball you have to cash in there," Red Sox manager Bobby Valentine said. "We're in the dugout if he makes the play."
Cook had a sick feeling after the game.
"Yeah, I feel awful," said Cook. "I let the team down. We're trying to win games, and that was a game we should have won. It's a play I've made 100 times. I just didn't get my feet set. We lost because I made an error."
Angels: Pitching woes continue
After posting an ERA of 3.33 in May and June, the Angels have a 5.45 ERA in 44 games since July 1. This month, the Halos have a 6.76 ERA, the highest in the Major Leagues. The bullpen has a 5.99 ERA in 36 games since the All-Star break.
Albert Pujols hit his 28th homer of the season -- the 473rd of his career -- on Sunday, pulling within two of Stan Musial and Willie Stargell for 28th on the all-time list.
Trout hit his 24th homer on Sunday.
Red Sox: Crawford to have surgery
Carl Crawford's second season with the Red Sox started late and ended early. The left fielder will undergo Tommy John ligament transfer surgery on Thursday to repair a tear in his left ulnar collateral ligament.
The Red Sox made the announcement early Monday evening. Dr. James Andrews will perform the surgery.
Sunday night's game against the Yankees was the last of an 11-day, 10-game road trip -- Boston's longest of the season. The Red Sox were 4-6 on the trip, going 2-2 in Cleveland, 1-2 in Baltimore and 1-2 in New York.
Angels starting pitchers were 2-6 with a 7.57 ERA and 13 home runs allowed during the 10-game homestand they just completed.
With Felix Doubront placed on the 15-day disabled list on Saturday, the Red Sox have had 26 players land on the DL this season for 30 separate stints, both of which are the most by a Sox team in at least 41 seasons.