Melbourne Victory have suffered the first loss of their Asian Champions League 2 campaign, falling to two second-half goals in a 2-0 defeat to Indonesian champions Persib Bandung.

Putting the hosts ahead just seconds into the second stanza, Montenegrin striker Balsa Sekulic's sucker punch brought the game to life after a first half as moribund as it was sweaty at the Si Jalak Harupat Stadium in Java on Wednesday.

The goal prompted both sides to finally raise their game but the Australians couldn't find a goal as they battled the stifling 93% humidity, even though they came closest when Santos's shot hit the underside of the bar, with Charles Nduka's follow-up cleared by the Indonesians' defence.

But the dangerous Sekulic drove a dagger through their hopes in the 67th minute when Persib got out in transition and sprung him into the box to score the decisive second.  

Without some key players and rotating others after travelling to Indonesia just days after their 1-1 draw in the Melbourne Derby - Guillermo May was absent and Jack Warshawsky was standing in for Jack Duncan in goal - the result left Giovanni Savarese's side's Asian adventure at a crossroads. 

Triumphant in all three of their continental hit-outs, Persib moved to nine points in group E with the win, putting them in a position to advance to the knockout stages by winning their return fixture against Victory next Wednesday. 

Elsewhere in the group, FC Seoul put The Cong-Viettel to the sword in their clash in Hanoi, running out 5-0 victors to claim their first win of the campaign, vaulting the Vietnamese side and moving to within a point of Victory. 

After rotating his squad throughout their first two continental games, Seoul boss Kim Gi-dong deployed close to a first-choice XI for the trip to Vietnam, something he's signalled will continue after his side wrapped up the Korean title last weekend. 

But with just one win in their last five matches, Victory will first need to prepare for an A-League Men visit from the Central Coast Mariners on Sunday.