SEATTLE — A deal is a deal, and the SuperSonics should stay.

That was the message from city of Seattle lawyers as a federal trial began today to determine whether the NBA franchise will be forced to stay at KeyArena until its lease expires in 2010.

SuperSonics owner Clay Bennett is trying to move the team — Seattle's oldest professional sports franchise — to his hometown of Oklahoma City, two years before the lease expires. Bennett, who sat expressionless at the defense table, is hoping to pay Seattle no more than $10 million in lost rent for the next two seasons.

In his opening statement, Seattle lawyer Paul Lawrence said the city only agreed in the mid-1990s to spend $84 million to renovate the old Seattle Coliseum — now KeyArena — because the team agreed to stay until 2010. He told U.S. District Judge Marsha Pechman the city has every right to hold the Sonics to that bargain, and asked her to force them to stay.

Bennett knew full well the Sonics had been losing money at KeyArena and assumed that risk when his group bought the team for $350 million in 2006, Lawrence said.

"These are all sophisticated businessmen who know what it means to sign and assume a contract," he said. "They can afford the losses they knew were coming."

The opening presentation included photos of Sonics banners hanging from the rafters and excerpts from e-mails in which Bennett and other owners discussed their eagerness to move the team soon after buying it. Lawrence said the economic, cultural and charitable benefits the Sonics bring to Seattle are unique, hard to quantify and not something that can be simply paid off.

Forcing the Sonics to honor the lease would give the city two additional years to potentially reach a deal for a new arena, Lawrence said. He noted the NBA's approval to move the team is only good for one year.

"A lot can happen in two years," he said.

Sonics attorney Brad Keller began his opening statement by saying there were two key tenets to the Sonics lease: One, that they would play their home games at KeyArena for 15 years; and two, that the city would provide an "economically feasible" venue. Nowadays, KeyArena is "terrible," economically and physically, compared to other arenas in the league, he said.

The Sonics insist they would lose up to $65 million over the next two years in Seattle, but would make an estimated $18.8 million next season if allowed to move, because there's a better venue in Oklahoma City.

The 1994 lease agreement that was supposed to be a win-win for Seattle and the team has become a lose-lose, Keller said, and forcing the team to stay would be like forcing an estranged husband and wife to share the same roof.

"Like many relationships do, this relationship broke down," Keller said.

He said the Sonics spent millions of dollars working with lawmakers to get a deal for a new arena, to no avail, and suggested the Legislature's reluctance is an indicator of the state's indifference to the team. The city says the team's demands for a $500 million venue were unreasonable.

KeyArena "hasn't been a competitive NBA arena for many, many years," Keller said.

Keller also alleged the city's real intent in bringing the lawsuit is to bleed the Professional Basketball Club in hopes it will sell to a local group. He cited a PowerPoint slide that former Sen. Slade Gorton, a lawyer hired by the city, displayed during a strategic meeting at the home of former Sonics chief executive Wally Walker. The slide said the role of Gorton and others would be to "increase pain" of trying to leave.

Seattle Mayor Greg Nickels was the first witness to testify. He said $35 million remains to be paid on the principal from KeyArena's renovation.