George Hook: Trimble's injury is a fillip for Schmidt, but could be a disaster for Zebo
Trimble played superbly on his return to the international side in Cardiff last weekend and despite initial fears that a foot injury might keep him out of Ireland's World Cup campaign, Schmidt is optimistic that the Ulster wing will be fit to line out against Wales again tomorrow week.
If that proves to be the case, Trimble is a certainty to travel to England next month. But with a selection headache looming, it's likely that one or two from Zebo, Earls and Kearney will miss out.
If we take it that Trimble, Tommy Bowe and Luke Fitzgerald are the top three wings in Schmidt's pecking order, with Rob Kearney and Felix Jones also nailed-on to travel, that leaves one vacant position as cover in the back three. For me, it is far from a certainty that Zebo will be selected.
Last Saturday, Trimble showed why he is so highly regarded by the head coach. His composure under pressure from the boot of James Hook and Hallam Amos was magnificent and he put in some thumping tackles to disrupt the Wales attack. The bone-crunching hit on Eli Walker to gift Earls his try typified Trimble's strength in defence.
Zebo does not offer that defensive solidity. For all of his athleticism, Zebo remains puzzlingly indecisive under a high ball and his decision-making in defence has frequently been called into question.
Back in March, Zebo told 'Rugby World' magazine that he still plays with the freedom and instinct that he had as an eight-year-old starting out and that he will never change his approach to the game.
It is all very well relying on natural ability and gut instinct in one-off match situations, but that type of mindset on a long-term basis does not tally with the system and style that the coach is trying to implement.
Schmidt's influence has unquestionably forced Zebo to up his overall work rate around the pitch, but I wonder if there has been sufficient improvement over the past two years to satisfy the coach's high standards?
For every moment of Zebo genius, there are hundreds of other little details that he is duty bound to perform. His flair and off-the-cuff skills can only be accommodated if the bread-and-butter rugby comes first. Does Zebo tick the necessary boxes in the eyes of the head coach?
Earls is another interesting case. The 25-year-old's man-of-the-match performance in Cardiff reinforced his credentials as a viable option at centre and though wing remains Earls best position, his flexibility to shift around the back line gives him an advantage when it comes down to the final shake-up.
Zebo has been picked to start at full-back against Scotland tomorrow and, like Earls in Cardiff last weekend, I'm guessing Schmidt is trying to determine if Zebo can suitably cover two positions with the deadline for the final squad fast approaching.
The former Cork Con wing will never have a better opportunity to assuage any doubts that Schmidt might have as to his reliability in what is a key position. Defence and composure should be first on Zebo's priority list against the Scots. If he passes this test, he might just force the coach's hand when it comes to final selection.
The decision to start Gordon D'Arcy in the centre is a curious one, given he had no involvement during the Six Nations campaign. Darren Cave had one of his better outings against Wales last weekend, but it is difficult to make the case for his inclusion in the final cut.
Jack Conan is another player with a chance to impress tomorrow, especially given that the unfortunate injury suffered by Tommy O'Donnell has all but ended his chances of playing in the tournament.
The raft of injuries suffered by to Irish back-row forwards over the years would suggest that Conan has an opportunity push himself to the front of the stand-by list with a strong performance against Scotland.
O'Donnell's injury has assured Jordi Murphy of his place in the squad, but Conan, with his ability to switch across the back-row, could easily find himself part of the tournament at some stage.
It is a concern that Mike Ross is being wheeled out for a second start in two weeks, particularly given Martin Moore's struggle for fitness of late and the ongoing injury to Tadhg Furlong. If Schmidt has to rely on Michael Bent as back-up to Ross at tight-head, he might have to consider giving John Hayes a call.
Last weekend's outing in Wales was a positive start, but Schmidt will look for improvements across the board tomorrow. Ireland should win, but the overall performance, more than the result, will be foremost in the mind of the head coach.