And Seattle got the better of its rivals from Portland.
"I told the guys before the game, this career is so fleeting and there is so much uncertainty day to day ... but the one thing I know for certain is we beat Portland, period," Seattle defender Zach Scott said. "We're always going to be the team to beat. They can say there is a changing of the guard, they can say we're a group of stars and they are the team, but in the end we are the ones that are going to come out victorious."
Eddie Johnson flicked a header past goalkeeper Donovan Ricketts off a free kick in the 60th minute, and the Seattle Sounders made Dempsey's home debut memorable with a 1-0 win Sunday night over the Portland Timbers before the second-largest, stand-alone crowd in Major League Soccer history.
The crowd of 67,385 trailed only the first home game for the Los Angeles Galaxy in 1996 that drew 69,255. It topped the 66,452 that saw Seattle and Portland play last October at CenturyLink Field and was the largest for any match in Seattle, besting a friendly against Manchester United in 2011.
"Nobody compares to our fans. When they turn out in numbers like that, it's indescribable," Seattle coach Sigi Schmid said.
Johnson scored his fourth goal against the Timbers moments after his speed in the open field drew a free kick when he was chopped down by defender Pa Modou Kah. Mauro Rosales' curling ball into the box found Johnson wide open after he left defender Alvas Powell behind.
"We're going to keep suffering if we don't find goals and if we don't sort out set pieces," Portland coach Caleb Porter said.
It was Johnson's sixth goal in MLS play. Seattle improved to 35-0-8 in its last 43 games when scoring first and controlled the second half after Portland had the better chances in the first 45 minutes.
The Sounders moved into a tie for fifth place in the Western Conference with 37 points and still have at least one game in hand on the rest of their playoff competition.
"I like the occasion of it. I like to play in big games," Johnson said. "We know how much it means to the fans. We know how much it means to the organization, the importance of these games. But at the end of the day you want to step up in big games and show your value."
Seattle was on pace for another crowd of 60,000-plus before Dempsey's arrival. But the acquisition of the U.S. captain from Tottenham, plus Seattle's archrival being his first home match, pushed the stadium past its capacity.
Before the game, fans jammed Occidental Park north of the stadium for the annual pregame march to it. Flares were lit, songs were sung and full city blocks were crammed with fans in rave green.
And No. 2 jerseys with "Dempsey" across the back flooded the stadium.
Dempsey received the loudest screams when he was the last name announced during pregame introductions. Fans added Dempsey-related signs around the stadium, including "Dempseyland" on north stands.
He delighted the fans with his footwork and creativity. In the first half, he flicked a no-look pass to Johnson and nearly scored in the second-half on a modified scissor kick - he called it a "ninja kick" - as he tried to get his first goal for Seattle.
The Timbers weren't afraid to be physical with Dempsey, pushing him off the ball when they could. Kah was especially willing, drawing Dempsey's ire and a few shoves in the back. But it was his careless tackle on Johnson that led to the free kick that gave Seattle the victory.
"It's showing character. That's what you have to have in these types of games. Being able to push yourself to the limit but not too far," Dempsey said. "I thought the team showed a lot of character, kept a clean sheet, and Eddie does what he does. He comes up in big moments."
Portland had its chances to ruin the night for its rivals to the north. Portland's Darlington Nagbe had a shot from outside the box that was punched over the net by goalkeeper Michael Gspurning in the 88th minute. Andrew Jean-Baptiste's header was caught by Gspurning in stoppage time.
Gspurning was also forced to make a number of key saves in the first half, coming off his line to smother Ryan Johnson on a breakaway in the 16th minute and getting a bit of luck in the 37th minute when Diego Valeri's shot from outside the box curled but hit the goalpost flush and ricocheted away.
"Everyone knows we're a good team. It's just a matter of showing it," Ryan Johnson said. "They finished their chances tonight and we didn't. I think next time, we're going to come out on top."