SEATTLE — Tim Browne had trouble believing, even with a memo staring him in the face, urging him to be in his seat by 7:20 p.m. on Saturday for a special announcement from Sounders FC.

“It could only be one of two things,” Browne, a Sounders fan, said of his thoughts. “The biggest jerk move ever, or we got Clint Dempsey.”

To the excitement of more than 40,000 fans, the news was that the Sounders finalized a transfer of Dempsey, the 30-year-old American soccer star, from Tottenham of the English Premier League.

The Sounders made the announcement on the CenturyLink Field. Walking to a podium to his own rap video, Dempsey was asked by Sounders majority owner Joe Roth if he’d made a decision on which MLS team he’d like to join. Dempsey, 30, unzipped a gray sweatshirt to reveal his new Sounders rave green jersey.

After he thanked the crowd for its support, fire flared behind the northern goal.

“He’s literally the greatest American soccer player that ever played,” said Yosafe Murphy, 33, of Dempsey, who’s captain of the U.S. men’s national team. “And now he’s a Sounder. And in the prime of his career; that’s just insane.”

Draped in Dempsey’s national team jersey, Browne was thrilled he was suddenly supporting his favorite player. Dempsey, a 6 foot 1 midfielder, is the ninth designated player in Sounders history. He joins forward Obafemi Martins and midfield Mauro Rosales in the team’s current allotment of three.

A Texan, Dempsey last played in MLS from 2004-06 and was Rookie of the Year in 2004. He has the most Premier League goals by any American with 57.

Sounders fans hope Dempsey is the piece that can bump the team into the playoffs this season and possibly its first-ever MLS Cup.

“Clint is a proven winner, a leader and a competitor who we believe will raise the bar of this organization on and off the field,” general manager Adrian Hanauer said in a release.

Terms of the deal were not disclosed. But NBC Sports’ ProSoccerTalk website reported that Tottenham would receive a $9 million transfer fee — the highest in MLS history — and Seattle would guarantee Dempsey $32 million over the next four seasons. It would be the largest base salary ever given to an MLS player.

Dempsey’s immediate impact wasn’t just in cheers. In addition his national-team jersey being worn by men and women all over the stadium, nine-year-old Miles Miller scoured the Internet for a photo of Dempsey to cut out and tape to a chopstick. He made 20 of the signs for his row in Section 133.

“Having recently played in Seattle with the national team, I experienced the incredible atmosphere and passion from the supporters first-hand,” Dempsey said in a release, referring to a USA-Panama World Cup qualifier match in June. “It’s going to be an honor to represent the fans in Seattle.”

The Sounders made room on the roster for Dempsey by agreeing Thursday to a new contract with Shalrie Joseph. The veteran midfielder no longer counts as a DP.

“It’s nice that America has good players, let alone coming back to the MLS,” Browne said. “We’ve always been a runt league in the worlds’ eyes and we’re getting better. We’re not in the top, yet, but this (Dempsey) makes us move faster.”