England coach Gareth Southgate insists Conor Gallagher "deserves" his first call-up after he was promoted from the Under-21 squad for Monday's World Cup qualifier in San Marino.

The Chelsea midfielder has impressed during a loan spell at Crystal Palace so far this season and follows in the footsteps of Emile Smith Rowe in earning a maiden senior call-up as a replacement in the current squad.

Jordan Henderson, Jack Grealish, Raheem Sterling, Mason Mount and Luke Shaw all withdrew from the squad set to travel to San Marino, with Gallagher added to Southgate's ranks.

"We've been very impressed with him," Southgate said of the 21-year-old, who has yet to make his senior debut for Chelsea.

"We've tracked him for a very long time in his loan spells at Charlton, Swansea - we knew the staff there very well - at West Brom and now at Crystal Palace so in each loan he has done extremely well.

"He has started the season very well with Palace. We talked about him when we named the original squad as somebody we were keen to keep an eye on and I suppose it's one of the benefits of being with the Under-21s because it was an easy transition for us to bring him across."