The Rangers trio of Andy Goram, Alan McLaren and Stuart McCall are injured and have been withdrawn from Brown's original 23-man pool, which also lost Celtic's Tosh McKinlay and Colin Calderwood of Spurs.
However, O'Neil is the only addition to the squad to complete an 18-man selection. The 23-year-old defender suffered a serious knee injury on the eve of last season's Scottish Cup final and only returned to the Celtic side in February. After four full games he was dropped back in the reserves by Tommy Burns and was not in the squad for Saturday's 0-0 draw at Motherwell.
"I got a call telling me to report to Hampden," O'Neil said yesterday. "It was a huge surprise but a nice one. I know there have been call-offs and I am not first choice, but if you are there, at least you have a chance to stake a claim for Euro 96."
O'Neil, who has been capped for Scotland at various levels except full, said playing in the European Championship did not even cross his mind as he fought back to fitness earlier this season.
Chelsea's John Spencer is a strong contender to start up front while Brown will assess the Rangers striker, Ally McCoist, in training before deciding if he should win his 50th cap.
n A back injury has forced the Sheffield United goalkeeper, Alan Kelly, to withdraw from the Republic of Ireland squad for Wednesday's friendly against Russia at Lansdowne Road.Reuse content