Tennessee's defense allowed two touchdowns in the final four minutes of regulation and overtime in Sunday's loss to the Colts. They had surrendered just six points in the first 56 minutes.  (AP)

Tennessee Titans LB Colin McCarthy could sense something was amiss. Indianapolis Colts WR LaVon Brazill had just caught a slant with 4:11 remaining to set up a 4th-and-1 from the Tennessee 8. The Titans rushed only three linemen and the catch looked easier than it should have been.

McCarthy surveyed the situation and used his index finger to count the number of the Titan players on the field. The second-year linebacker stopped at 10. The Colts appeared to notice that the Titans were a player short and quickly called a power run with seven men on the line. Indianapolis capitalized on the substitution error and gained seven yards for a critical first down.

“I was running down to get the official’s attention but they snapped the ball before we could get the timeout called,” Titans coach Mike Munchak said. “We thought we had the substitution right and ended up not having it. Guys are coming both ways, so a lot of times you’re not sure what you have.”

It was one of several miscues by the defense in the waning moments of Sunday’s 19-13 overtime loss to the Colts. The Titans held the Colts to six points in the game’s opening 56 minutes before allowing two late touchdowns in the defeat.

On the second play of overtime, the Titans allowed a 19-yard run up the middle by Colts RB Donald Brown. Before the snap, McCarthy moved from the middle of the field to the right edge to blitz Colts QB Andrew Luck. As McCarthy blitzed, the Colts crossed LG Jeff Linkenbach and RG Mike McGlynn on a trap play. With a wide split between DTs Jurrell Casey and Sen’Derrick Marks, Brown had a clear path. A combination block from McGlynn and LT Anthony Castonzo also kept DE Kamerion Wimbley out of the middle.

“It was good timing. It’s not something they checked into or audibled into,” Munchak said. “It’s one of those things where you get the right play called against the right defense.”

The Colts won the game on a 16-yard catch by RB Vick Ballard in overtime. Luck rolled to his right on a "fake toss 39 taxi naked screen" play and threw to his left, just beyond the reach of Wimbley in the flat. S Robert Johnson said Monday that the Bills ran a similar play against the Titans in Week 7.

“We were prepared, we just overplayed it,” Johnson said. “Kamerion was there and just missed it by a couple inches. That’s what it is in the NFL.”

The Titans could have won the game in regulation after recovering an apparent fumble by Colts TE Dwayne Allen. The ball was jarred loose by LB Akeem Ayers, but it was ruled that Allen’s forward progress had already been stopped. Munchak said the team has not yet filed a formal complaint with the league office.

“I always think forward progress is when you have four guys pulling a guy back and they blow the whistle,” Munchak said. “At that time I didn’t hear a whistle and I thought the ball was out before anything was ruled one way or the other.”

Report -- TE Cook requests trade: Munchak reiterated that Jared Cook is a valuable part of the offense after The Tennessean reported Monday that indications are the fourth-year tight end has requested a trade.

“For me, that’s not something we’ve thought about at all, so I’m hoping that’s not on his mind either,” Munchak said.

Cook is tied for second on the team in catches with 28 and is second in receiving yards with 373. In Sunday’s loss, Matt Hasselbeck overshot Cook on a potential game-winning touchdown with 1:15 left.

“Jared has made a lot of great catches for us this year,” Munchak said. “We know for us to win games we need him making plays for us.”

Cook has appeared in 280 of the Titans’ 497 offensive plays (56.3 percent), according to NFLGSIS.com. In Tennessee’s last two games, Cook played in 45.5 percent of the Titans’ snaps. Hasselbeck has targeted Cook 13 times over the Titans’ last three contests. During that span, Tennessee's leading receiver, Kendall Wright. received 16 targets.

A third-round pick by the Titans in 2009, Cook is in the final year of a four-year, $2.45-million contract. Cook was unavailable for comment Monday.

Injury update: Munchak said that for now, Hasselbeck will be the starter for Sunday’s game vs. the Bears. Jake Locker underwent an MRI on Monday on his left shoulder, but the results weren’t available at the time of Munchak’s weekly press conference Monday. Munchak said Locker needs additional clearance from doctors before he can throw in traffic in practice.

RG Leroy Harris (knee) and WR Kenny Britt (knee) also underwent MRIs on Monday. Harris had his foot caught under a Colts' lineman in the first quarter of the defeat. Munchak is unsure if Harris’ injury is season-ending.

“I’m healthy. I’m the same as I was the last couple weeks,” Britt said. “I just got an MRI today to see if everything is all right.”

Munchak is optimistic that LT Michael Roos (abdomen), CB Tommie Campbell (ankle) and LB Will Witherspoon (hamstring) will return to practice this week. All three were sidelined by the injuries against the Colts.

For more up-to-the-minute news and analysis on the Tennessee Titans, follow Matt Rybaltowski @CBSTitans.