David Beckham could accomplish a lot by adding an MLS Cup to his resume

David Beckham is restless.

Sure he has one of the most impressive resumes in English soccer history, with six Premier League titles, two FA Cups, a UEFA Championships and the captaincy of the English national team. He gets the biggest paycheck in U.S. soccer, has a former pop star for a wife and lives in an $18.2-million Beverly Hills villa with Tom Cruise and Jay Leno among his neighbors.

Yet he remains unsatisfied because of one thing he doesn’t have: an MLS Cup, the top soccer prize in this country.

“It would definitely be one of the biggest things that I’ve ever won,” Beckham says, “because of people saying, ‘What are you going to do?’ and ‘What are you going to achieve?’ People are kind of expecting that to happen.”

Last weekend’s 1-0 win over Seattle in the first leg of the Western Conference semifinals moved the Galaxy 90 minutes closer to a league championship and Beckham that much nearer redemption heading into Sunday’s elimination rematch with the Sounders at the Home Depot Center.

Pressure is nothing new to Beckham, who has been saddled with great expectations — and biting criticism — since he joined the Galaxy in 2007.

He was single-handedly expected to make soccer relevant in the U.S. and he was given a contract — $32.5 million over five years — worthy of the challenge.

By some measures he’s succeeded. Average MLS attendance has grown and his presence helped draw other aging international stars, such as Mexico’s Rafael Marquez and France’s Thierry Henry. Beckham also helped the league land a record eight-figure television deal, and last season it began a wave of expansion that is expected to see the MLS add five teams from 2009 to 2012.

Still, the league is hovering around the break-even point financially and it narrowly avoided a players’ strike last winter.

And, on a personal level, a series of injuries and two in-season loans to AC Milan caused Beckham to miss more than half the Galaxy’s matches since 2007, calling into question his commitment to both the Galaxy and the league and earning the disdain of even the home fans.

Which brings us back to the MLS Cup, the Holy Grail that could burnish Beckham’s reputation in the eyes of many critics while making his U.S. adventure a clear success.

For Galaxy Coach Bruce Arena, adding a title here to the ones Beckham won in England and Spain would provide a bold exclamation mark to the midfielder’s stellar career.

“If he can cap off his career with a domestic championship in the United States, you don’t need to say anything more. It would be a fantastic accomplishment for him individually,” Arena says. “This has been a tough road for him. And he’s dealt with a lot of criticism. By winning this year, it would help shut up some of those people.”

Beckham has already begun converting some naysayers, starting in his own locker room.

“He’s part of our team. And in the beginning it wasn’t always that way,” says Galaxy captain Landon Donovan, who clashed repeatedly with Beckham in their first two seasons but now uses words such as “committed” and “engaged” to describe his teammate.

“He’s shown how much he cares about this team,” Donovan says. “He takes interest in all the guys’ personal lives and talks to people. And it helps because when he speaks, people listen.”

But nothing Beckham has said in the last three years echoed as loudly as his determination to come back quickly from the torn Achilles’ tendon injury he suffered in March while playing for AC Milan. The injury was a psychological and physical blow, ending his hopes of playing for England in a fourth World Cup and leaving him to face a difficult eight-month rehabilitation few 35-year-olds in the twilight of their careers would probably attempt.

“Obviously with this kind of injury, I could have gone and sat on the beach and just said ‘see you next season,’ ” Beckham says.

Instead, he made it back in six months, joining the Galaxy for the last eight matches of the regular season. And though he has clearly lost a step and can be quiet for long stretches of a game, he still has a flair for the dramatic, scoring a game-winning goal in one match and setting up the game-winner in another.

“Now you can tell he’s engaged and wants to be a part of this,” Donovan says of Beckham, who clearly played through pain in the Galaxy’s playoff opener on Seattle’s unforgiving Field Turf. “He wants to be out there and be a part of it. And it’s nice for us to see that he wants to be so committed in that way.”

Beckham says he will prove his commitment in another way too, passing up a clause in his contract that would have allowed him to leave the Galaxy after this season. Nor does Beckham, who has a year left on his MLS contract, plan to play in Europe this winter.

“I find it hard to sit still and do nothing … but at the end of the day I need to rest my legs,” he says. “Waking up in the morning, it still takes me a while to get the leg going and it’s still pretty painful.”

Beckham’s focus now is on delaying the off-season. The home-and-home playoff series with Seattle will be decided on aggregate goals. With the Galaxy leading, 1-0, it needs only a tie Sunday to advance to the Western Conference championship against the winner of the FC Dallas-Real Salt Lake series.

A win there would return Beckham to the MLS Cup final, giving him another chance to silence his critics and join Trevor Steven as the only English players to win domestic titles in three different countries.

“There’s always a satisfaction when you prove people wrong,” Beckham says. “I’ve been able to do that over the years. Yeah it was great winning FA Cups, Champions League, playing in World Cups, winning [Spanish] La Liga. But now I’m playing in a MLS team and the MLS Cup is the biggest thing in soccer in this country. So it’s an exciting prospect.”

So is the possibility of more international stars following Beckham to MLS. And that, more than any titles he wins, could be Beckham’s legacy in U.S. soccer.

“It used to be we had to go chase [European players]. We’ve had a lot of people that are interested in coming now,” says Tim Leiweke, president and chief executive of Anschutz Entertainment Group, the investor-operators of the Galaxy.

Henry, for example, didn’t commit to the league until after talking with Beckham, Leiweke says.

“David is a great ambassador,” Leiweke says. “But he’s more than a just an ambassador. He can still play.”

Although there were times when Beckham appeared to prefer Europe over L.A., he now says he’d like to make California his family’s home even when his playing days are over.

“Our boys go to school here. They’re happy here,” says Beckham, the father of three children, ages 5 to 11. “As long as they continue to be happy here, my wife’s happy here, then we plan on staying.”

He’s even considering U.S. citizenship.

“I hope so, one day. It would be nice,” he says. “I’m English born and bred. And that’s the way I’ll always be. I’m an Englishman, you know.”

kevin.baxter@latimes.com