Williamson sustained an ankle injury during England's remarkable win over Sweden in the quarter-finals.

England came back from 2-0 down to progress 3-2 on penalties in a shootout in which nine of the 14 spot-kicks were either missed or saved.

Williamson returned to camp wearing a protective boot, but Morgan, who would be a potential candidate to replace the Arsenal defender in Sarina Wiegman's line-up, is confident the England captain will be fit to play against Italy on Wednesday (AEST).

"We are very optimistic that Leah will be available," Morgan said. 

"She seemed in very high spirits this morning and I want what’s best for the team and that’s absolutely having our captain on the pitch for us."

Asked if she was prepared to step in, Morgan added: "I'm the same as every single game. Be prepared to play if I'm needed. I'll know the role, and just be absolutely ready to train at a high level over the next few days. But we're very optimistic that Leah will be fine."

England is the first reigning champion to reach a semi-final since Germany in 2013.

On those past five occasions that the reigning champion has featured in the semi-finals, it has gone on to reach the final. Germany did so in 1997, 2001, 2005, 2009 and 2013, with Norway the most recent side to be eliminated in 1995, when it lost 7-5 on aggregate to Sweden.

England has won seven of its past 10 games in all competitions against Italy, losing only two and drawing the other one, although it has lost each of the two head-to-heads at the Euros – in 1987 and 2009, both 1-2.

"Everyone who played significant minutes had a recovery day to be able to just sort of reset, get moving again. The finishers went to train and had a really intense session," Morgan said.

"It's just a case of getting off feet, bringing yourself back down to earth, even mentally, just to have a chilled day to reset after all of the excitement of the night before.

"Just everyone being able to relax, switch off a little bit, ready to then turn our full focus to the Italy game and be ready to go with full energy into that."