Republic of Ireland v Serbia - talking points
The Republic of Ireland returned from a disappointing trip to Georgia with questions to answer after their World Cup qualification bid suffered a significant blow.
Here, Press Association Sport takes a look at some of the talking points surrounding their attempt to resurrect their hopes of emerging from Group D, with leaders Serbia providing the opposition on Tuesday evening.
Robbie Brady announced himself on the international stage at last summer's Euro 2016 finals, in the process establishing himself as one of Martin O'Neill's key players. However, just where Brady - a winger by trade - can be employed to greatest effect remains a matter for debate. He has been used at left-back, as a wide midfielder and in Tbilisi, with Jeff Hendrick missing, in the number 10 role before dropping back into central midfield. And the way in which he is utilised against the Serbs will go a long way towards indicating O'Neill's game-plan.
O'Neill's preferred 4-2-3-1 formation relies upon the defensive protection provided by the two men sitting in front of the back four. With Hendrick and James McCarthy missing in Georgia, O'Neill paired veteran Glenn Whelan with Harry Arter in the engine room and the pair had great difficulty in getting to grips with a highly mobile Georgian midfield. But will he change either system or personnel this time around?
Record goalscorer Robbie Keane's retirement from international football has left a yawning chasm in Ireland's front line and a lasting solution is yet to be found. Shane Long was handed the job in Georgia, but was isolated for much of the game, while Jonathan Walters, who has more often than not started in a wide auxiliary midfield role, and Daryl Murphy are options, as is midfielder James McClean depending on how bold O'Neill feels he needs to be.
No-one will know better than Newcastle team-mate Ciaran Clark what makes Serbia striker Aleksandar Mitrovic tick, and no-one will want to get one over on him quite as much. The combustible frontman joined up with his international colleagues having been suspended for three games on video evidence for elbowing West Ham's Manuel Lanzini. However, his six goals in the campaign so far have underlined a potential he has not always fulfilled at St James' Park and he will be a threat if he is allowed to be.
Three successive draws have taken the edge off Ireland's encouraging start to the campaign and, having flown out to Georgia level on points with Serbia and four clear of Wales and Austria, they returned two adrift of the former with their advantage over the latter reduced by the same margin. Defeat by the Serbians would be a massive blow, another draw far from ideal, but a win would breathe new life into their Russian dream.