Slovakia coach Jan Kozak has questioned whether England's promising youngsters can deal with their tag as Group B favourites at Euro 2016.
Kozak's men kick-off their round-robin campaign against Wales in Bordeaux, with England facing Russia in Marseille later on Saturday.
Breakthrough talents such as Dele Alli and Marcus Rashford feature in Roy Hodgson's 23 and Kozak - whose squad incidentally has the highest average age in the competition at 30.7 - is unsure over how they will fare.
"Regarding the group I think the top favourite is England because they have a squad of very good quality players," said the former Czechoslovakia international at his pre-match news conference.
"But, of course, it is a tournament and there is a lot of pressure on young English players.
"I am curious to see how they cope with that pressure. With regards to other teams in our group, I think it will be very even.
"Russia, Wales and Slovakia all have certain qualities that can be effective, but it will depend on the performance on the day with these teams."
Marek Hamsik inspired Slovakia to their first berth at the European finals with five goals in qualification.
The Napoli midfielder believes international friendly draws against the Republic of Ireland and Northern Ireland over the past three months will stand his team-mates in good stead for what Wales have to offer.
"Recently we have played Ireland and Northern Ireland so I suppose it will be similar type of play," he said, speaking alongside his coach at the Stade de Bordeaux.
"There is nothing to be ashamed of regarding our performances against these two opponents and if we play like that tomorrow we can be happy.
"They have one of the top players in the world in Gareth Bale so we have to be really focused. I think it will be an open game with Wales."