Aaron Ramsey is one of seven Wales players who could miss out on a World Cup first-leg play-off if they are cautioned in Monday night's game against the Republic of Ireland.
Victory for either side in Cardiff will guarantee them at least a second-place finish in Group D, but both teams could also finish first if Serbia slip up at home to Georgia.
James Chester, Ben Davies, Andy King, Joe Ledley, Hal Robson-Kanu and Ashley Williams are the other Wales players walking a tightrope heading into Monday's game, live on Sky Sports Football from the Cardiff City Stadium.
The match will be refereed by Slovenian official Damir Skomina, who presided over England's loss to Iceland at Euro 2016.
Skomina also took charge of Wales' stunning 3-1 quarter-final win over Belgium in the same tournament, booking four Welsh players.
One of those players was Ramsey, with the midfielder's yellow card ruling him out of Wales' 2-0 semi-final defeat to eventual winners Portugal.