Mauricio Pochettino has told teenage Tottenham defender Juan Foyth to show he can deal with the rough and tumble of English football.
Pochettino has taken a softly softly approach with £10million summer signing Foyth, easing him into English football slowly.
But his fellow Argentinian faced his first big test when Tottenham take on bitter local rivals West Ham in the Carabao Cup 's last 16 on Wednesday night.
The 19-year-old, signed from Estudiantes in August, enjoyed an armchair ride on his debut — and only senior appearance for his new club so far — in the previous round against Championship visitors Barnsley.
But he can expect a far sterner test from Andy Carroll at Wembley.
The powerful 6ft 4in striker is available for the Hammers after being suspended for last Friday's loss to Brighton following his sending off at Burnley the previous weekend for two yellow cards picked up for clattering James Tarkowski and Ben Mee in quick succession.
Spurs boss Pochettino, who was a defender in his playing days, said: "Foyth is young, but he needs to show why is here. And maybe then he has the possibility to play. You will only know if he is ready to play if he plays.
"Maybe in the future, if some players are suspended or maybe we have some injuries, then we'll play with him.
"I remember playing when I was 17 or 18 against a massive striker — and I'm smaller than Juan.
"I'd say, 'Come on. You need to show.'
"Juan's at Tottenham now. He needs to fight and prove that he can compete in these type of games."
Pochettino will rest most of his big-hitters for Spurs' fourth game in just 11 days — with Saturday's lunchtime trip to Manchester United and a Champions League return against Real Madrid on Tuesday looming.
Tottenham have not won a trophy since doing so in this competition in 2008, but Pochettino added: "Our objective is to try to win the Premier League and the Champions League.
"For me, [those are] two real trophies. That can really change your life.
"I would like to win the Carabao Cup. But I think it will not change the life of Tottenham.
"I think we need to teach our fans, because it's so difficult to fight for four competitions."