Late in the January transfer window he was transferred on loan to Japan's Machida Zelvia with an option to buy, and on Tuesday on his first start for the club he doubled his seasonal goals tally to book them top seeding in the Asian Champions League Elite knockout round.
Wearing the No.99 shirt Yengi struck after seven and 55 minutes in a 3-2 win over Chengdu Rongcheng that snuffed out the Chinese side's slim prospects of advancing.
Curtis Good was also on the mark as Thailand's Buriram United claimed a 2-0 win over Shanghai Shenhua to confirm their progress.
"I thought our first half was really good," said former Socceroos defender Good, who put his side in front with a close-range header.
"We could have scored a few more goals. I thought the boys were excellent and it's good to have a win going into the next round."
Buriram are currently fourth in the table, which earns a home second leg in the next round, but can be overtaken by Melbourne City who complete their group programme against Gangwon FC on Wednesday.
Elsewhere Malaysia's Johor Darul Ta'zim reached the region's last eight with a 1-0 victory against already-qualified Vissel Kobe but FC Seoul squandered their chance to follow suit as they threw away a two-goal lead in stoppage time to draw 2-2 with Japan's Sanfrecce Hiroshima.
That result leaves the South Koreans sweating on the outcome of Wednesday's matches with both eighth-placed , Gangwon and ninth-placed Ulsan HD, who play bottom side Shanghai Port, able to overtake them.
In the West region Roberto Mancini's Al-Sadd suffered a 4-1 thrashing at the hands of Saudi Pro League champions Al-Ittihad but scraped through due to a 2-0 loss for Qatari compatriots Al-Gharafa against Iranian outfit Tractor FC.
The first eight finishers in both east and west Asia advance to the last 16, which will be played on a home-and-away basis in March.
The tournament's quarter-finals, semi-finals and final will then be held in Jeddah in a centralised format in April.
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