Tsedenbal's spot-kick two minutes into the second half meant Mongolia held on to claim a 3-2 aggregate win over Brunei, who had initially cancelled out the visitors' first-leg advantage thanks to a first-half brace from Razimie Ramlli.
The Mongolians are joined in the draw for the next phase of qualifying by Bangladesh, Guam, Malaysia and Cambodia after they came through their respective second-leg encounters on Tuesday.
Cambodia were given a scare when Hassan Bashir netted a first-half penalty to give Pakistan hope of overturning their 2-0 first leg deficit with 45 minutes remaining.
But Keo Sokpheng slotted past Pakistan goalkeeper Yousuf Butt after 64 minutes to calm Cambodian nerves and Reung Bunheing struck from close range in the final minute to ensure a 2-1 win on the night and a 4-1 aggregate victory.
Malaysia, meanwhile, made easy work of Timor-Leste, with Shahrel Fikri scoring a hat-trick in a 5-1 win that completed a 12-2 aggregate success over the two legs.
Jason Cunliffe also scored three as Guam overturned a first-leg loss to oust Bhutan with a 5-0 victory on Tuesday as the United States territory secured a 5-1 aggregate win.
And Bangladesh advanced despite being held to a 0-0 draw by Laos in Dhaka, with their 1-0 win in the first leg last week enough to ensure they go through to the second round.
Sri Lanka will have to wait to learn their fate after their scheduled meeting with Macau was cancelled due to a refusal by the team from the former Portuguese enclave to travel to Colombo for the second leg of their meeting.
Macau, who won the first leg 1-0 in the southern Chinese city of Zhuhai last Thursday, cited security concerns for their refusal to travel and the matter has been referred to FIFA.
The second phase of Asia's four qualifying rounds for the 2022 World Cup will commence in September, when 40 nations will compete for one of 12 berths in the third phase of the competition.
Asia has four guaranteed places at the finals while Qatar, who are the current Asian champions, qualify automatically as hosts. Another spot at the finals is available via an inter-confederation playoff.
(Reporting by Michael Church, Editing by Toby Davis)
