Axel Witsel and Anthony Modeste played a major part getting Tianjin Quanjian into the Asian Champions League quarter-finals but the Chinese side must contest the biggest game in their short history without the star duo.

Belgian international Witsel joined Borussia Dortmund earlier this month and striker Modeste is set to sign for Galatasaray, putting the onus very much on Alexandre Pato when Tianjin face Japan's Kashima Antlers away in Tuesday's first leg.

Pato has rediscovered his vim since joining Tianjin from Villarreal 18 months ago, the Brazilian scoring 10 goals in 12 Chinese Super League (CSL) games this season.

He has been a rare shining light for a team that has struggled under coach Paulo Sousa and Tianjin are mid-table in the CSL, though they have been more convincing in the Champions League.

A sense of crisis has threatened to engulf the club in recent weeks with influential midfielder Witsel leaving for Germany, Frenchman Modeste agitating for a move away and the side's CSL form tailing off alarmingly.

It is a far cry from nine months ago when, led by Italian World Cup winner Fabio Cannavaro, Tianjin qualified for the Champions League for the first time since their founding 12 years ago and were a club on the up.

They at least arrested their domestic slide with a 1-0 home victory over bottom side Guizhou Zhicheng on Friday, but Sousa admitted it was hardly impressive.

"Overall, the quality of our play was not good, especially going forward," said the Portuguese, whose side reached the last eight of the Champions League on away goals against CSL champions Guangzhou Evergrande -- when Tianjin still had Witsel and Modeste.

"It was very poor," Sousa said bluntly of the narrow Guizhou win, according to the Tianjin Daily newspaper, before adding: "I believe that the team will get better and better after getting through this most difficult period."

Tianjin travel to a Kashima side who have their own problems.

The club are seventh in the J-League after conceding an injury-time penalty in a 1-1 home draw with mid-table Jubilo Iwata on Friday.

Kashima's home form has been a problem throughout the Champions League this season, winning just once in four matches in Asia's top club competition in front of their own fans -- 3-1 over Tianjin's CSL rivals Shanghai SIPG in the last 16.

Midfielder Kento Misao is wary of the threat posed by the 28-year-old Pato.

"He's really fast. I'm really looking forward to playing against him," he told the AFC website.

"I think there will be times when he drops a little deeper and looks to influence the game and make chances from in behind, so we have to keep in mind the danger he could pose from there."

In the other quarter-final first legs this week, Iran's Esteghlal host Al Sadd of Qatar, Qatar's Al Duhail host Iran's Persepolis and Jeonbuk Motors are home to Suwon Bluewings in an all-South Korean affair.