Martinez admits he is excited about the potential exhibited by the former Sligo Rovers man.
He told evertontv: "[Seamus] is still a young man in football terms and at such a young age, he's just going to develop and get better and stronger.
"It's great to see players have used the pre-season well and are making that impact from the start.
"I think we have some outstanding young players in this squad that they very much balance the experience and wisdom of the senior figures in the group."
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