European champions Italy and England can qualify for the 2022 World Cup on Monday but Cristiano Ronaldo's Portugal will have to wait until next year to battle through the playoffs.
Portugal crashed to a 2-1 loss to Serbia on Sunday that sent the winners through to the finals in Qatar and forced Portugal into the playoffs in March as the second-placed team in Group A.
Croatia, the beaten finalists in 2018, and Spain also qualified on Sunday.
Gareth Southgate's England have the simplest task on Monday as they will book their ticket if they avoid defeat away to minnows San Marino.
Italy though have put themselves in a difficult position after they only drew 1-1 with Switzerland on Friday when Jorghino missed a late penalty.
The Italians lead Switzerland at the top of Group C only on goal difference, with only group winners guaranteed of a spot.
Roberto Mancini's side now take on the already-eliminated Northern Ireland in Belfast knowing they need to match Switzerland's result against Bulgaria, assuming the Swiss do not win with a clear enough margin to overturn the two-goal gap separating the two teams.
The Northern Irish haven't scored against Italy since 1961.
- Made to wait -
Ronaldo's hopes of playing in a record-equalling fifth World Cup hang in the balance after Aleksandar Mitrovic scored a vital goal just before stoppage time to give Serbia a 2-1 victory that guaranteed them a place in Qatar.
Spain and Croatia secured their places in Qatar on Sunday thanks to 1-0 wins over Sweden and Russia respectively.
But Portugal slumped despite opening the scoring after just two minutes through Renato Sanches.
Serbia bounced back to dominate the remainder of the first half and deservedly levelled when Dusan Tadic's strike squeezed in off the post after Dusan Vlahovic had hit the woodwork.
Manchester United forward Ronaldo was kept quiet as another chance to score his 800th career goal came and went.
Instead the crucial goal came from Mitrovic, who a year ago was the only Serbian player to fail to score in a penalty shootout against Scotland that led to his nation missing out on Euro 2020.
The Fulham striker steered in Tadic's header at the back post, prompting wild celebrations from the Serbian bench.
"It was an amazing game," said Mitrovic. "We were the better team today in every aspect of the game."
Portugal must now navigate two tricky one-off playoff matches in March to maintain their record of qualifying for every major tournament since the 1998 World Cup.
"We must apologise to the Portuguese but my team will be at the World Cup, that's guaranteed," said Portugal coach Fernando Santos.
"We will have to prepare well to beat our opponents in March and to get to Qatar. But I always trust my players."
Spain made sure of their place as Alvaro Morata's goal four minutes from time ended Sweden's resistance in Seville.
The Swedes' shock 2-0 defeat to Kazakhstan on Thursday had handed 2010 winners Spain pole position in Group B, meaning La Roja just needed a point to qualify.
Morata made his mark off the bench with the only goal of the game after Robin Olsen had turned Dani Olmo's blistering shot onto the bar.
"To be honest, it is a huge weight off my shoulders," said Luis Enrique. "I felt much more pressure in these games when people think it is easy to get a result than in the Euro or the Nations League."
Croatia also needed a late winner as an own goal from Fedor Kudryashov snatched qualification from Russia in a battle in boggy conditions in Split.
Croatia looked bound for the playoffs as they toiled on a waterlogged pitch against a resolute Russian defence.
But Kudryashov's error saw them snatch top spot from the visitors eight minutes from time.
North Macedonia secured the playoff place behind the four-time world champions with a 3-1 win over Iceland.