Mayo captain Diarmuid O'Connor is set to miss the rest of the season after breaking his wrist in training.
The two-time Young Footballer of the year suffered the injury, which leaves a hole in midfield for James Horan's side, at training on Tuesday night.
Mayo are already without midfielder Matthew Ruane in the middle - who's out with a broken collarbone - but will be encouraged by potential returns to fitness for Donal Vaughan and Seamus O'Shea.
The 2017 All-Ireland finalists are in the midst of another summer in the back door after defeat at the hands of Roscommon in Connacht, but got off to solid start in round three of the qualifiers last weekend away to Down.
But they face a much tougher challenge this weekend as MacHale Park plays host to a clash with Armagh - with the Orchard men in buoyant form after dumping heavyweights Monaghan out of the Championship over the weekend.
The crucial qualifier gets underway at 7 pm on Saturday June 29.
If you haven't already, be sure to like our Irish Mirror Sport and Irish Mirror GAA pages on Facebook and follow us on Twitter.
