Shattered Adelaide United defender Nigel Boogaard has apologised for his brain fade which turned the tide against his club in their Asian Champions League quarter-final.

The Reds were leading 2-0 against Uzbekistan's Bunyodkor in Wednesday night's first leg of the quarter-final at Hindmarsh Stadium, when Boogaard was sent off.

Boogaard pulled down Bunyodkor striker Kamoliddim Murzoev as they chased a long ball, with the Uzbeks scoring from the resultant free kick.

A 10-man Adelaide then conceded another goal in the second half to draw 2-2 - Bunyodkor's two away goals worth double ahead of the second leg in Tashkent on October 3.

Boogaard said he felt responsible for Adelaide's predicament.

"I apologised to everyone individually when they came into the change rooms for the situation I put them in," he said.

Adelaide captain Eugene Galekovic said Boogaard's blemish gifted the visitors a "change of luck".

"Obviously he's shattered," Galekovic said of his teammate.

"But these things happen in football and we have got to move on.

"He's sorry, he apologised straight away, he knew he was at fault."

Galekovic said given Adelaide's 2-0 advantage, established by goals from Iain Ramsay and Evan Kostopoulos in the initial 18 minutes, the draw felt like a loss.

"The boys are a bit disappointed but ... we know that with 11 players we outplayed them," he said.

"We knew they were going to come at us, obviously playing with 10 men we had to try and stop them and it was going to be hard to score ourselves.

"We defended well but they got through a few times and in the end they scored a couple and made it tough for us."