Junior Negrao struck two first-half goals and goalkeeper Jo Su-Huk came up with a flurry of saves as Ulsan Hyundai Motors powered through to the semi-finals of the Asian Champions League with a gripping 2-0 win over Beijing Guoan on Thursday.

Both teams had cruised into the last-eight phase of the competition unbeaten, but it was Ulsan who continued their hot streak by winning their seventh successive match since landing in Qatar last month, and in the process staying on course to claim the title for the second time.

Ulsan first achieved the feat in 2012 when they outclassed Beijing twice in the group stage during a menacing nine-game winning run that culminated in their 3-0 victory over Saudi Arabia's Al Ahli in the final.

"It was a very important win and I am happy that we got the result and showed our quality throughout the match," said Ulsan coach Kim do-hoon.

Having lost all their previous four encounters at this level against Ulsan Hyundai, Beijing Guoan knew history was heavily loaded against them when they took the field at the Al Janoub Stadium.

But despite a gallant effort, especially in the second half when they dominated, Beijing failed to find the goal that might have brought them back into the match.

Negrao had come to Doha with a huge reputation, having scored 26 goals in 27 matches in the K League 1 this year to finish as the top-scorer by a considerable distance.

But the 33-year-old Brazilian started in just three games as Ulsan coach Kim do-hoon preferred others such as Yoon Bit-garam.

On Thursday though he again proved their mainstay, first scoring from the penalty spot in the 21st minute after Beijing's South Korean star Kim Min-jae handled the ball inside the area.

Beijing went close a few minutes later when Jonathan Veira's powerful drive from just outside the box was punched away to safety by Jo Su-huk, one of at least 10 saves by the Ulsan goalkeeper on a busy day.

Negrao struck for the second time in the 42nd minute with a 30-yard bullet, the ball thundering into the net despite Beijing goalkeeper Hou Sen's full-stretch diving effort.

Beijing controlled a lively second half and created a number of fine chances only to see them blocked or deflected away by Jo or the Ulsan defenders.

"The team played well, we got lots of possession and made a lot of shots, created our chances but could not take them," said Beijing coach Bruno Genesio, clearly frustrated that his team could not win despite enjoying 61 percent possession.

"We missed the last touch a bit. The factor that decided the match was efficiency inside the box. We committed a couple of mistakes and they punished us."