Asia's top trio all scored three times against Middle Eastern opposition, making them strong favourites to reach the third and last round in Thursday's away legs.
Korea DPR, China PR shocked
However, Korea DPR, who played their first FIFA World Cup™ since 1966 last year, are up against it after losing 1-0 at home to United Arab Emirates, courtesy of Ali Mabkhout's 56th-minute strike.
China PR also lost 1-0 at home, to Oman. Hussain Al Hadhri silenced Shanghai's Hongkou Stadium crowd with a strike after just three minutes, which was enough to seal a vital victory for the away side.
"It is not over. The players all tried their best and we believe we still have a chance in Oman," said China PR coach Miroslav Blazevic.
"Oman were lucky that they got a gift from us at the start of the match. This advantage gave them more confidence and a mental advantage, but if we could have equalised quickly then it would have been a different game."
The continent's leading teams are all in action for the two-legged ties, with the winners split into three groups of four for the final phase, which finishes in March next year.
Hoffman headed home a Sebastian Ryall cross in the 14th minute, as Australia had nine attempts on goal before Yemen's first shot was saved by goalkeeper Andrew Redmayne on the half-hour.
Nichols added Australia's second in the 67th minute after a cross by the ever-present Hoffman, who rounded off the scoring in stoppage time.
"It could have been more to be honest. We missed some really easy chances and their goalkeeper made some outstanding saves as well," said coach Aurelio Vidmar. "We're pleased with that and now we'll hopefully go to Newcastle and finish it off."
Korea Republic were made to work harder for their win and had to come from a goal down after Jordan's Mahmoud Saleem Mahmoud Za'tara opened the scoring in first-half injury time.
But Kim Tae-Hwan equalised 11 minutes into the second half before midfielder Yoon Bit-Garam calmly converted a penalty with 13 minutes to go. Substitute Kim Dong-Sub increased their margin with an 86th-minute header.
As Japan peppered the Kuwait goal, Cerezo Osaka midfielder Hiroshi Kiyotake nodded the opener on 18 minutes before Mizuki Hamada grabbed a second headed goal eight minutes before half-time.
And Japan were cruising when Kashima Antlers forward Yuya Osako poached the third just after the hour-mark. But Jaber Jazea pounced on a defensive mistake on 68 minutes to give Kuwait hope of pulling off a huge upset later this week.
"It was a disappointing game, because we let in a goal. We could have scored more goals. But we can go to Kuwait in very good form," said Kiyotake.