Defending South Korean football champion FC Seoul enjoyed a dominant victory, while three other South Korean teams were each held to a draw at the top Asian club football competition this week.

The 2013 Asian Football Confederation (AFC) Champions League kicked off with four K League Classic clubs in group stage action.

FC Seoul, the 2012 K League Classic champ, trounced Jiangsu Sainty of China 5-1 in their Group E clash in Seoul on Tuesday, but three other K League Classic sides, Jeonbuk Hyundai Motors, Pohang Steelers and Suwon Samsung Bluewings, only walked away with one point apiece.

Three of the past four AFC champions have come from the K League Classic. And with the resounding win, FC Seoul looked determined to make it four out of five for the first-division South Korean league.

Dejan Damjanovic, the K League Classic scoring champ and MVP from last year, scored twice against Jiangsu, and Yun Il-lok, one of FC Seoul's prized offseason acquisitions, also grabbed a brace.

Mauricio Molina added another goal.

Choi Yong-soo, FC Seoul's head coach, said his players may have been "hungry."

"I think the guys were just desperate to show our home fans the fruits of their hard work from the offseason," Choi said. "They put in long hours and grew more confident with each passing day."

Choi said he will not get carried away by one win.

"Only the starting gun has gone off," he said. "We will run full speed until the finish line."

Two teams in action on Wednesday, Suwon and Pohang, were both scoreless in their respective draws.

Suwon's goalkeeper Jung Sung-ryong stopped a late penalty against Central Coast Mariners of Australia in their Group H match that ended 0-0. Jung had earlier made another crucial save on Mitchell Duke to keep Suwon in the game.

Suwon dominated possession in the opening 20 minutes without threatening to score. North Korean striker Jong Tae-se made his Suwon debut after signing with the team last month but was largely ineffective. He didn't record his first shot on goal until the 82nd minute.

Pohang, the 2009 AFC champs, played a goalless draw against the visiting Beijing Guoan in Group G. In the spirited contest, Pohang almost got on the board with seven minutes left, but Hwang Jin-sung's header was cleared by Beijing defender Xu Yunlong just off the line after goalkeeper Yang Zhi was caught out of position.

Pohang head coach Hwang Sun-hong lamented his team's lack of finishing touch around the net.

"We would have taken a good position with a win at home and I'm disappointed we only got a draw," he said. "Football is a cruel game because dominance (in possession) doesn't ensure you the proper result."

Earlier on Tuesday, Jeonbuk Hyundai Motors settled for a 2-2 draw against Thai champion Muangthong United in their Group F contest. Jeonbuk, the 2011 AFC runner-up, blew a one-goal lead in the final moments of the away match, as defender Jung Hyuk headed a corner into his own net.

Fabio Lefundes, the interim head coach for Jeonbuk, shrugged off the loss and said the team will try to do better the next time.

"We wanted three points, but it was a very hard game," he said.

"This is the first game, and we will try to get three points in the next game."

In the opening stage, there are eight groups of four. The top two countries from each will make up the round of 16.

The championship match had been a one-and-done affair from 2009 to 2012, but the AFC will return to a two-leg format this year, with the matches held once each at the finalists' home stadiums.

This format was used from 2003 to 2008.

The opening leg of the final will be on Oct. 26 or 27, and the second leg will be on Nov. 8 or 9. (Yonhap News)