Chelsea boss Thomas Tuchel had no problems using Christian Pulisic as a wing-back against Arsenal on Sunday.
With Ben Chilwell, Marcos Alonso and Emerson Palmieri unavailable, winger Pulisic was thrown in defence.
"He played there with me at Dortmund and we played many times like this with Callum," Tuchel said after the 2-1 victory.
"Marcos wasn't able to play today so we put Callum on the left side, which I wanted to see from a long time. Callum can maybe be more dangerous from this position coming inside which he loves, and which he did today. So you know our situation.
"We have Azpi and Reece for this position [right wing-back] but Azpi only started two days ago and Reece hasn't even started yet. So we need solutions because we start on the 11th against Villarreal and on the 14th is the season. We can't try things then so now is the time to see.
"It was the possibility to give him some minutes and from here we go on."
