Wales are aiming for the win against the Republic of Ireland in Cardiff on Monday night that would secure a World Cup qualifying play-off place.
The winners will finish at least second in Group D, with a draw enough for Wales to end up in that position.
Second place means a potential play-off spot for Russia 2018.
However, should group leaders Serbia slip up at home to Georgia, both teams have a chance to secure an automatic World Cup place.
Serbia are only a point ahead of Wales and two ahead of the Republic after their 3-2 defeat in Austria on Friday.
A draw would not guarantee Wales reaching the play-offs, but a win to finish second will be enough to guarantee one of the eight play-off places on offer from the nine groups, after Bosnia-Herzegovina lost to Belgium in Group H on Saturday.
Gareth Bale remains on the sidelines for the home side, who have seven players one booking away from a suspension that would mean they missed the first leg of the play-off.
Wales beat Georgia 1-0 on Friday – their first away qualifying victory without Bale since a 1-0 win over Azerbaijan in 2009.
Captain Ashley Williams believes the Irish will spring “no surprises” in the Welsh capital.
Martin O’Neill’s team are still missing regular captain Seamus Coleman, whose leg was broken by Wales defender Neil Taylor when they drew in March.
Midfielders James McClean and Robbie Brady are available after missing the 2-0 win against Moldova through suspension.
What the managers say
Wales manager Chris Coleman
“We’re on dangerous ground if we go in with a game plan of trying to soak the pressure up for 90 minutes.
“We are too good to do that. We’ll go and attack, go and score goals. We have to do that – it’s our strength.
“A point may be OK, but we’ll go for three points. That’s the way it’s set up.”
Martin O’Neill, Republic of Ireland manager
“I think we can win the match. I felt it was always going to be like this. When we get off to a decent start (in qualifying), the mindset changes a little bit in terms of points.
“But if you had said to me right at the beginning when the group was drawn that we’d have to go to Wales and win – and we were down as fourth seeds – I would have taken it. So let’s go for it.”
- The Celtic rivals’ head-to-head record is that each have won five game with four draws. But the Republic have the only competitive wins from those games, 1-0 in March, 2007 in a Euros qualifier and another in 2011 when they beat Wales 3-0 in the Nations Cup.
- Two more competitive games ended in draws, 2-2 in the 2007 rematch and 0-0 during this qualifying campaign in March, 2017.
- Wales have reached the World Cup only once, in 1958, and made their second major tournament since then by going to the 2016 Euros in France, where they went out in the semi-finals.
- The Republic made the first of three World Cup appearances in Italy, 1990 where they reached the quarter-finals.
- They are ranked 34th in the world, 21 places below Wales.