Phillips broke up Marcus Mariota's pass attempt, the Titans' second after a defensive penalty on the first attempt, and the Chargers held on for a 20-19 victory on Sunday at Wembley Stadium.
It was the fourth consecutive victory for the Chargers (5-2), who weathered the absence of running back Melvin Gordon to a hamstring injury and relied upon their defense to pull out the win.
"It was a great decision," Phillips said. "That's the game right there. If I'm the head coach, I go for it, too. You have the momentum. You just (went) 70 yards. You've got one of the biggest running backs in the game, one of the best running quarterbacks in the game and one of the best third-down running backs in the game - and a receiver corps that had been doing good all game - so why not?"
The Titans (3-4) drove 89 yards over the final 4:55 before Mariota's 1-yard pass to tight end Luke Stocker pulled them within one point.
Mariota, who went 24 for 32 for 237 yards with an interception, thought he had scored the touchdown himself.
With 40 seconds left, he ran 3 yards on a draw and stretched for the end zone, but replay showed that he was down inches shy of the goal line.
After Stocker scored, Mariota's first attempt was a pass intended for Tajae Sharp, an incompletion negated by a defensive holding call on the Chargers' Casey Hayward, and his second, toward Taywan Taylor, was tipped by Phillips.
"I loved the call," Mariota said. "I love that he has confidence in us to go make that. We just didn't execute."
Gordon entered the game third in the NFL in rushing with 466 yards and had scored a total of nine touchdowns this season, but was ruled out after an unsuccessful pregame workout.
Austin Ekeler, in his second season, earned his first start in Gordon's place and ran for 42 yards on 12 carries, but it was quarterback Philip Rivers who shouldered the burden for the Chargers.
Rivers, who completed 19 of 26 passes for 306 yards, threw two touchdown passes - one that went 75 yards to Tyrell Williams on Los Angeles' first play from scrimmage, and one that traveled 55 yards to Mike Williams to cap the first drive of the second half.
The Titans trailed 10-6 at halftime after two field goals by Ryan Succop.
After Mike Williams scored, the Titans ended their 10-quarter skid without a touchdown when Derrick Henry ran 1 yard into the end zone with 9:43 left in the third quarter to pull within 17-13.
Michael Badgley made his second of two field goals, Succop missed from 51 yards and after holding Los Angeles, the Titans prepared their final charge.
Dion Lewis ran for 91 yards on 13 carries, including a 36-yard gain on the final drive that moved Tennessee into the Chargers' territory, and Tajae Sharpe had seven catches for a career-high 101 yards.
Rivers and wide receiver Keenan Allen were shouting at each other and had to be held apart after an incompletion to Mike Williams in the end zone on third-and-7 early in the fourth quarter.
Allen, who had beaten Titans cornerback Logan Ryan on the play and was wide open, kicked a pylon in frustration before targeting Rivers.
"He ran a route so good that he felt like he needed the ball - and he should," Rivers said. "That's fine. At the same time, the coverage was going his way, so I went somewhere else. It's a passionate, emotional game. That won't be the last argument that any of us have on the sideline and I won't worry about it after 2 seconds."
A BAD DECISION
Inside linebacker Denzel Perryman handed Mariota the first red zone interception of his career at the Chargers 4-yard line with 30 seconds left in the first half.
"That was a big mistake," Mariota said. "I should have moved onto my second read and maybe we would have had a shot."
Los Angeles left tackle Russell Okung had his right fist raised during the anthem, but put it down before the start of "God Save The Queen."
Tennessee: Right guard Josh Kline was injured with 43 seconds remaining, was replaced by Corey Levin and did not return.
Los Angeles: Philips injured an ankle late in the second quarter, Hayward required attention after a hit on Mariota before halftime and Mike Williams also needed a moment after a hard fall in the fourth quarter, but all returned.
Tennessee: Hit the road for a Monday night game against the Dallas Cowboys on Nov. 5.
Los Angeles: Travel to face the Seattle Seahawks on Nov. 4.
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