A moment of magic from Hulk set up Elkeson for the only goal as Shanghai SIPG sealed their place in the last 16 of the AFC Champions League on Tuesday.
The burly Brazilian forward burst past Ulsan FC fullback Lee Myung-jae in the 50th minute with power and pace before cutting back the deftest of passes to give his countryman a simple finish.
But the Chinese side had to ride their luck for the 1-0 win in South Korea as Ulsan squandered a succession of chances in the Group F encounter.
Ulsan will in particular be cursing a crazy couple of minutes that should have seen them go to half-time with at least a one-goal advantage.
Yohei Toyoda shot wide in the 39th minute and within 60 seconds the Japanese striker inexplicably blazed over from just two metres out when it seemed easier to score with the goalmouth gaping.
Two minutes later, with the SIPG defence still all at sea, Richard Windbichler found space at the edge of the six-yard box but the Austrian cannoned a right-foot volley against the crossbar.
Earlier in Group F, Kosta Barbarouses fired home a dramatic last-minute winner to keep Melbourne Victory in the hunt for the last 16 with a 1-0 victory against Kawasaki Frontale.
The teams were deadlocked until the New Zealand winger got on the end of a chest-down from Terry Antonis in the 90th minute to smash home with his left foot for Melbourne's first win of the campaign.
It lifts Victory to five points, behind Ulsan on goal difference, and those two teams are set to clash next in the South Korean city on April 4.
'NEVER GIVE UP'
Shanghai SIPG are unbeaten on 10 points at the top and guaranteed a place in the knockout stages while Kawasaki, quarter-finalists last year, are bottom and look to be heading out with just one point.
"To be fair, I thought we had control of the second half and the persistence of this team, we're always going to get chances," Barbarouses told Fox Sports.
"We never give up."
Qualification from Group H is still wide open after leaders Kashima Antlers drew 1-1 at home to Sydney FC on Tuesday.
Unbeaten Antlers looked on their way to a third win in four matches this term when Mu Kanazaki's close-range header gave the Japanese side a 27th-minute lead.
But Sydney clung on to their dwindling hopes of qualification with 20 minutes to go when Luke Wilkshire's cross was met at the back post by the head of Matt Simon and bundled over the line.
The Australian side remain rooted to the bottom of Group H on two points with Kashima top on eight.
Suwon Bluewings are second, a point behind Kashima, after Dejan Damjanovic's second-half strike and Choi Sung-kuen's 88th-minute clincher gave them a 2-0 win at Shanghai Shenhua's Hongkou Stadium.
Shenhua, who also lost 2-0 at home to SIPG in the Chinese Super League Shanghai derby last weekend, remain winless on three points with just two matches to go.