The 22-year-old, who has scored 10 Premier League goals so far this season, was left out of the Three Lions squad for the March international break, which was announced last Friday.
Instead, he joined up with England's Under-21s side, who face friendlies against France and Portugal in the next few days.
However, it has since been confirmed that Delap - alongside Southampton's Taylor Harwood-Bellis and Crystal Palace's Adam Wharton - will train with the England senior squad at St. George's Park this afternoon ahead of Friday's World Cup qualifier against Albania at Wembley.
Harwood-Bellis is a one-cap England international who scored on his debut against Ireland back in November. Wharton, who also has a single cap to his name, was named in the squad for Euro 2024.
Chelsea's Cole Palmer has dropped out of Tuchel's squad for this month. He's been replaced by Morgan Gibbs-White of Nottingham Forest.
You can watch a live stream of today's England training session here.
An update from St. George's Park as three U21 #YoungLions players join in today's #ThreeLions training session.
Cole Palmer remains with Chelsea for further assessment on an injury sustained in club training last week.
— England (@England) March 18, 2025