John Joe Patrick Finn Benoa has dropped out of the Republic of Ireland U21s trio of friendlies to focus on upcoming school exams.
The 17-year-old Getafe midfielder qualifies to play for Ireland through his father, who hails from Ballyhaunis in Co Mayo. He's also eligible for Spain and Cameroon.
Finn Benoa had been due to link up with the U21s for the first time but, will have to wait to pull on an Irish jersey for the first time as he concentrates on his education.
Sheffield Wednesday defender Ciaran Brennan has also been ruled out of the trip due to illness, so Watford's highly-rated Bosun Lawal and Anselmo Garcia McNulty of Wolfsburg will link up with the squad in Marbella.
Ireland play Switzerland at 11am Irish time, with the match live on the RTÉ Player.
Defender Garcia McNulty, who has a Spanish father and Irish mother, was on the U17s team during their 2019 European Championships campaign. He moved to Wolfsburg from Real Betis two years ago and is currently captain of the German outfit's youth team.
Sevilla's Ryan Johansson remains in the squad. He looks set to finally represent Ireland after receiving FIFA clearance to play for Ireland last week.
"I had a very positive conversation with John Joe and from that discussion it was clear the appropriate thing to do was to allow him to put his full focus into his upcoming exams," said Crawford.
"He was very excited by the call-up and is looking forward to being involved in the Irish set-up in the near future.
"Unfortunately, Ciaran Brennan hasn’t been able to make the trip as he’s sick and we wish him a speedy recovery.
"We decided to bring in Bosun, who has done very well at Watford’s academy this season, and Anselmo Garcia MacNulty who likewise has performed well for Wolfsburg this campaign. It’s an opportunity for both players to impress in training."
Bray Wanderers’ Brian Maher, Bohemians pair Dawson Devoy and Andy Lyons and UCD’s Colm Whelan will join-up with the squad after their respective League of Ireland fixtures this weekend.
Lincoln City’s Sean Roughan will also fly into Spain next week with his club side in English Football League play-off action.
Republic of Ireland squad
Goalkeepers: Sam Blair (Norwich City), Brian Maher (Bray Wanderers), Dan Rose (Schalke 04)
Defenders: Anselmo Garcia McNulty (Wolfsburg), Festy Ebosele (Derby County), Shane Flynn (Leicester City), Andy Lyons (Bohemians), Oisin McEntee (Newcastle United), Mark McGuinness (Arsenal), Lewis Richards (Wolves), Sean Roughan (Lincoln City).
Midfielders: Bosun Lawal (Watford) Luca Connell (Celtic), Conor Coventry (West Ham United), Dawson Devoy (Bohemians), Alex Gilbert (Brentford), Conor Grant (Rochdale), Ryan Johansson (Sevilla), Conor Noss (Borussia Mönchengladbach), Louie Watson (Derby County).
Forwards: Jonathan Afolabi (Celtic), Will Ferry (Southampton), Joshua 'JJ' Kayode (Rotherham United), Gavin Kilkenny (Bournemouth), Colm Whelan (UCD), Tyreik Wright (Aston Villa).
30 May - Switzerland v Republic of Ireland, 11am, Dama de Noche Football Centre, Marbella, (Live on Premier Sports 1/ FreeSports)
2 June - Australia v Republic of Ireland, 12pm, Marbella Football Centre, Marbella (Live on Premier Sports 1/ FreeSports)
5 June - Republic of Ireland v Denmark, 5pm, Dama de Noche Football Centre, Marbella