Yuichiro Nagai gave the J.League champions the lead 22 minutes into the game before Yuki Abe headed home in the 71st minute to seal a 2-0 win over Sepahan at a packed Saitama Stadium.

They defeated the Iranian side 3-1 on aggregate to capture the first part of a possible domestic and continental treble.

With the Reds leading the J.League and also in contention the Emperor's Cup - as well as playing in December's FIFA Club World Cup - the club could be celebrating an unprecedented trophy haul come New Year's Day.

But despite the significant number of commitments that still lie ahead for his team, Osieck and company were ready to let their hair down for at least a few hours.

"There's not a lot of time to celebrate because our schedule is very tight and the next game is on Sunday," said Osieck, whose side face Shimizu S-Pulse in the league this weekend.

"I read in the newspaper that everybody is doing their best to hunt us and give us a tough time and do something for their image.

"That's normal when you are a winning team, people try and trip you but I think it's really a day to celebrate because this is really something special.

"We have achieved something really great, something that has never been done before in Japan. Today is the time to celebrate and tomorrow we will focus on our game on Sunday against S-Pulse."

Marcus Tulio Tanaka's return to the heart of the defence after missing the first leg in Esfahan was one of the keys to Urawa's victory and Osieck praised the Brazil-born defender.

"The mere presence of Tulio makes a difference," said the German.

"He is our general in defence, he's doing a lot on the field of play, he's dangerous at set plays and he is one of our most prolific players.

"It's essential for the team that he is ready to play. Tulio is part of the team, an essential part of the team but he is nothing without the other players and I want to stress that fact."

Meanwhile, Sepahan coach Luka Bonacic admitted his cautious approach in the first half may have cost his side the title.

Sepahan's performance showed a marked improvement from the last time they faced Japanese opposition in Japan, when they eclipsed Kawasaki Frontale in a penalty shootout in the quarter-finals, but in the end it was not enough.

"Maybe I made a mistake, maybe from the first minute I should have gone 3-4-3 like in the second half - but now it's too late," admitted the Croatian.

"The last three or four weeks we have done some excellent work with Emad Ridha and we had much better fitness, mentality and tactics than against Kawasaki.

"Against Kawasaki my team was not in good physical condition."

Victory for Reds, though, has not denied Sepahan the opportunity to play at the FIFA Club World Cup in December, when the Iranian side will face off against Waitakere United from New Zealand in the tournament's opening match.

"It's true I'm disappointed but it's not too much after this evening," Bonacic said.

"First of all we must play against a team from New Zealand. I don't expect too much against the New Zealanders, they have the same quality as us. Last year it was Auckland FC and this was my club for 18 years as a player and a coach, but now I don't know which team is coming for us.

"But it will be a great experience and we will make a job for this."