Buriram concede six in AFC Champions League opener vs. FC Seoul

FC Seoul's Brazilian striker Adriano put four goals past hapless Buriram United as the South Koreans thrashed the 10-man Thai champions 6-0 in the AFC Champions League (ACL) on Tuesday night.

The Thunder Castle -- unbeaten domestically in 2015 and unlucky to exit last season's ACL on goal difference in the group stages -- were brought back to earth on home soil on Match Day One of Group F.

Buriram will point to the controversial early decision to deny them a penalty when former player Osmar Ibanez appeared to bring down Diogo Luis Santo in the box. The home side's star man had to go off injured while Ibanez stayed on the pitch.

But this cannot deflect attention from a shambolic and undisciplined defensive performance in front of their home fans from Alexandre Gama's men who had high hopes of reaching the later stages of this season's competition.

Captain Suchao Nutnum characterised the side's lack of discipline when he was red-carded for a nasty challenge when the side were already three goals down.

There was a scrappy opening to the game and Buriram's new signing Kaio Felipe was shown a yellow card after just five minutes for an elbow on FC Seoul midfielder Kim Won Sik.

The hosts had their first spell of pressure after nine minutes when a foul on Kaio set up a free-kick near the right touchline. Theerathon Bunmathan whipped in a dangerous ball, which Ibanez headed behind at full stretch.

Suchao's corner was then flicked across goal by Go Seul-Ki but no Buriram players were in a position to get on the end of it.

The home side then had a huge call for a penalty denied in the 13th minute. Suchao's ball down the right put Diogo through on goal and the Brazilian got goal side of Ibanez. The Spaniard's clumsy challenge knocked Diogo off balance but when the striker went down, the referee waved play on.

Insult was added to injury for Gama's side as Diogo left the field injured. Midfielder Adul Lahso replaced the Brazilian as the hosts had to reorganise.

Buriram were further incensed minutes later when Anawin Jujeen's shot appeared to be defected behind but a goal-kick was awarded. Referee Mohammed Abdualla Hassan had to have a stern word with Suchao for taking his protests too far.

The game settled and the visitors came back into it. In the 28th minute, Dejan Damjanovic turned Suchao in the middle of the park and struck a beautiful pass out left to Adriano. The Brazilian striker stepped inside the challenge of Chitipat Thanklang and side-footed the ball past Siwarak Tedsungnoen to put the South Koreans 1-0 ahead.

The goal rattled the home side and Andres Tunez was soon given a warning for a rash challenge on goal-scorer Adriano.

In the 34th minute, only desperate defending stopped the visitors from taking a two-goal lead. Damjanovic was given a clear sight on goal but Adul threw himself in front of the ball to block.

And the hosts had another let-off minutes later when a corner broke to Sin Jin Ho. The midfielder's powerful strike from 12 yards looked net bound until his teammate Adriano got in the way.

But it wasn't long before the visitors' superiority paid off and Buriram had only their own poor defending to blame. In the 40th minute, Ju Se Jong floated a simple ball over the middle of the home defence and Adriano ran through to lob Siwarak and put the K-League side two goals in front.

Before half-time, Kaio had a chance to reduce the deficit but he was too hesitant when put through on Yoo Hyun's goal and was eventually crowded out.

Defender Suree Sukha came on for the second half. But, after just five minutes, he was the guilty party as Buriram's defence was once again undone by a simple pass from the middle of the park. When Yojiro Takahagi slipped a low ball towards Adriano, Suree made a woeful attempt to play the Brazilian offside. Instead, Adriano was left with time and space to shoot high past Siwarak and complete his hat trick.

If things weren't bad enough, the hosts soon went down to 10 men when their skipper Suchao was red-carded for a studs up lunge on Takahagi. Vice-captain Tunez then picked up a yellow card for his complaints as Buriram's discipline started to completely desert them.

And Adriano soon added his fourth on the hour mark, with Suree again failing to defend effectively His attempted clearance from Damjanovic's cross fell straight to the Brazilian inside the box and Adriano gratefully accepted the chance to rifle home.

In what was fast resembling a training ground exercise for the visitors, Adriano then found space down the right and crossed low for Damjanovic to tap home number five in the 67th minute.

And there was still time for FC Seoul to strike a sixth goal when Lee Seok Hyun worked an excellent one-two with Park Chu Young and raced through to fire past Siriwak.

Gama now has a huge job on his hands to rebuild his side's confidence ahead of next week's trip to face Shandong Luneng in China. On the evidence of this performance, simply avoiding a thrashing might be considered a positive result.