Madeley and Frazer are facing fitness battles ahead of Euros
Luke Madeley is a major doubt for Ireland's European Championship bid in Antwerp next month after breaking a bone in his foot during a training session in Dublin.
The Three Rock Rovers defender - son of former Banbridge and Ireland player Robin Madeley - is wearing a protective boot at present.
With under three weeks left before the start of the Euros, it seems unlikely that the 23-year-old will have recovered in time for the trip to Belgium.
Ireland continue their preparations over the weekend when they face Scotland in two internationals in Glasgow today (3pm) and tomorrow (12 noon).
Nine Ulster players are included in head coach Alexander Cox's panel, with Bann striker Johnny McKee earning a recall after almost a year's absence.
The 22-year-old said: "I was obviously disappointed not to make the cut for the World Cup but I've been enjoying being back training with Ireland and I'm delighted to be in the squad for the games in Glasgow."
The Scottish double header will act as a dress rehearsal for the teams' meeting in the group stages of the Europeans.
Meanwhile, there are growing concerns over the fitness of Megan Frazer for the women's Euros which run concurrently with the men's event.
The Ulster woman hasn't played for close to two months after aggravating a knee injury during the FIH Hockey Series in Banbridge.
Frazer hasn't made the squad to face Italy at Stormont tomorrow (3pm) in the first of a two-match test series which concludes on Tuesday at the same venue (3pm).
UCD's Ellen Curran has been called up as a replacement, with goalkeeper Lizzie Murphy, who comes in for Emma Buckley, the only other change from the squad that defeated Scotland 2-1 in the recent series at Stormont.
Among the seven Ulster players in the squad is Pegasus defender Shirley McCay, who is set to extend her record tally by winning her 287th cap tomorrow.