SEATTLE — The pressure was more than just a metaphor during Charlie Whitehurst’s first possession in his first game for the Seahawks.

The Tennessee Titans’ defense was front-loaded at the line of scrimmage, baring its teeth for a blitz.

Whitehurst wasn’t fazed. Not by the Titans. Not by the fact this was his debut for a team that traded away a draft pick for the right to sign him to a new contract this offseason even though he had never attempted a regular-season pass.

Whitehurst altered the play at the line of scrimmage, changing receiver Mike Williams’ route via hand signal. The result: a 51-yard touchdown pass to Williams and a postgame nod of acknowledgment.

“Really, hats off to Charlie,” Williams said. “He recognized it.”

Yes, indeed. Five months after his acquisition was greeted with skepticism, he passed for 214 yards and both of Seattle’s touchdowns after replacing starter Matt Hasselbeck in the second quarter of a 20-18 victory over Tennessee at Qwest Field in coach Pete Carroll’s debut.

Whitehurst was eight of 12 in the second half. He threw a 36-yard pass to Deon Butler on fourth-and-two and then capped that drive with the touchdown that gave Seattle the cushion it needed.

Former Oregon running back LaGarrette Blount scored a 1-yard touchdown for Tennessee with 4:35 left, and the Titans cut Seattle’s lead to two after a two-point conversion. The Titans got the ball back with a minute left when safety Kam Chancellor sealed the victory with an interception of Rusty Smith, Tennessee’s third quarterback.

Now, before anyone gets too carried away, it was only an exhibition game — the first of four, Whitehurst himself pointed out. And he wasn’t perfect, having a pass intercepted in the second quarter after driving into Tennessee’s territory.

Entering the game, some wondered whether he might lose the backup job to J.P. Losman. Now, the question is whether there might end up being a bona fide competition at quarterback at some point this season. Seattle acquired Whitehurst to be a potential quarterback of the future, and Saturday against Tennessee he looked like exactly that.

Not that Whitehurst was ready to announce his arrival just yet.

“It’s nice to go out there and play well, but it’s the first preseason game,” Whitehurst said. “We’ve got three more preseason games, we’ve got a long season. You like to go out and play well every time. It’s nice that it was the first one, but it doesn’t mean all that much.”

That’s true. Seattle was undefeated in exhibition games last season, which didn’t do much to prevent the Seahawks’ 5-11 belly flop in the regular season.

Tennessee’s starting quarterback, Vince Young, played only two possessions. Chris Johnson, the NFL’s reigning rushing champ, carried five times for 7 yards and scored the Titans’ only touchdown.

But there were some things worth noting.

Left tackle Russell Okung acquitted himself well despite having only a week of practice. He was the only one of Seattle’s starters who appeared in the second half. Olindo Mare kicked two field goals of more than 40 yards.

Seattle’s pass defense began Saturday’s exhibition game a lot like it ended last season: hemorrhaging yards. Young completed all four passes he attempted on Tennessee’s first drive, accounting for 70 of the Titans’ 79 yards on the play.

Young was five of six, and the only pass the Titans didn’t catch was grabbed by Seattle cornerback Josh Wilson. He intercepted a first-quarter pass after starting ahead of Kelly Jennings on the right side of Seattle’s secondary.

Pass pressure is the biggest question mark on Seattle’s defense, and defensive end Chris Clemons and linebacker Dexter Davis each had a sack, and Red Bryant continued to thrive after his switch to defensive end.

But, Seattle gave up some pressure, too. Hasselbeck was knocked down on his first pass attempt of the game and sacked to begin his second series under center. Hasselbeck was four-for-nine passing for 26 yards. He played Seattle’s first three possessions, leaving the game after Mare’s 44-yard field goal in the first minute of the second quarter.

He was replaced by Whitehurst, who completed all three passes he attempted on his first drive, which culminated with the 51-yard touchdown to Williams, who ran a curl, spun upfield away from Titans cornerback Ryan Mouton and ran untouched for a touchdown.

Whitehurst had Seattle moving on the next possession, too. Whitehurst threw into double coverage and outside of Williams. Mouton didn’t even have to break on the ball to pick it off.

But that was the only significant flaw in Whitehurst’s debut, and while the exhibition game isn’t exactly the stiffest test, it was one he passed to the tune of more than 200 yards.