Gareth Southgate admits he faces a daunting task in trimming his Euros squad after Adam Wharton's eye-catching England debut added to his list of positive headaches.

After a sluggish start, an experimental Three Lions side eased to a 3-0 victory over Bosnia and Herzegovina on Monday night, thanks to goals in the final half-hour from Cole Palmer, Trent Alexander-Arnold and substitute Harry Kane.

Southgate handed opportunities to several fringe squad players, including Crystal Palace midfielder Wharton, who was playing Championship football at Blackburn only five months ago, but capped his rapid rise by making his international bow off the bench.

"There's no question he's impressed us," said Southgate, who must whittle his 33-man squad down to a final 26 by Saturday. "We saw things in his performances for his club that showed [here].

Gareth Southgate on Adam Wharton

"The biggest thing is to see a picture and play it forward early. That sounds really simple, but that hasn't been so simple for us over seven or eight years, that type of player."

Wharton was one of the breakout stars in the second half of the Premier League season after moving to Selhurst Park in an £18million deal during the January transfer window.

The 20-year-old completed all 36 of his passes during an impressive half-hour cameo, and his emergence has added to Southgate's midfield options in what has been a persistent problem position.

"I think the other players have recognised his quality very quickly," Southgate added. "The positions they take, the way they interact on the training pitch.

"Whenever we call a new player in, they always doubt what we're doing and think we don't know what we're doing. Then they work with these youngsters and go, 'Okay, now we see why'. We see them a lot more than anybody else. I think he showed in the little cameo what we've seen in training in the last week and what we've seen with his club."

Wharton's Palace team-mate Marc Guehi said: "Adam making his debut today was fantastic, he looked so composed. He just looks comfortable, looks like he's been playing forever."

Southgate will get one more chance to asses his players in Friday's Wembley friendly against Iceland, when the likes of Kane, Declan Rice and several other certain Euros starters are expected to return to the line-up.

While several young players in Southgate's squad look likely to be cut, including the uncapped Jarrell Quansah and James Trafford, positive performances from the likes of Wharton, Eberechi Eze and the under-pressure pair of Jack Grealish and James Maddison means there are tough calls to be made.

"Of course [it's going to be difficult]," Southgate said. "We understand the significance for all the players, so we are giving it the respect and consideration it deserves to make fair, right decisions.

"It is always going to be subjective and we have to balance what we need in every area of the pitch as well, so that is the added complication. It is not just getting the best individuals in, there is a positional element to that as well."