Declan Rice has been contacted by England and may opt to represent the Three Lions instead of the Republic of Ireland, says Martin O'Neill.
The West Ham teenager has started three friendlies for Ireland, making his debut in March, but is able to change allegiance as he has not yet played a competitive fixture.
Rice has not been named in O'Neill's preliminary squad for Ireland's meeting with Wales in the Nations League on September 6.
And O'Neill fears the 19-year-old, who can play in either defence or midfield, may make the switch to England.
"He is still deliberating. He is a young man," O'Neill said.
"England have spoken to him. He is taking time to make his mind up. He has done brilliantly for us. I'm giving him a little bit of time.
"I wouldn't be exaggerating to say Declan has loved it with us. After the Turkey game [Rice's senior Ireland debut] his father was there and it was a joyous moment for them.
"We have done everything we can. He has been welcomed by the squad, the fans. He is taking time and I am respecting that."
O'Neill: I wouldn't be exaggerating to say Declan has loved it with us. After the Turkey game his father was there and it was a joyous moment for them. We have done everything we can. He has been welcomed by the squad, the fans. He is taking time and I am respecting that. #COYBIG— FAIreland (@FAIreland) August 27, 2018
Rice's situation mirrors that of Aston Villa winger Jack Grealish, who represented Ireland at youth level before declaring for England in 2015.
The 22-year-old, linked with a move to Tottenham in the transfer window, has played for England's Under-21 side but is yet to feature for the senior team.
His only start in the Premier League this season came in West Ham's opening 4-0 defeat at Liverpool, where he was substituted at half-time.