Mats Hummels is expected to return alongside Jerome Boateng in Germany's defence for Thursday's game against Poland. DANIEL ROLAND/AFP/Getty Images

Mats Hummels is closing in on a return to the Germany team for Thursday's Euro 2016 match against Poland, after training with his teammates in midweek, but Poland keeper Wojciech Szczesny is an injury doubt.

Germany centre-back Hummels, 27, took his place alongside Jerome Boateng in training on Tuesday, meaning that goal scorer Skhodran Mustafi might have to settle for the bench in the Poland match.

Hummels sustained a calf injury in the DFB Pokal final on May 21 and only resumed team training with the national team at the weekend.

Should Hummels return to the starting XI, Mustafi is set to be demoted to a bench role despite scoring the first goal for Germany against Ukraine last Sunday and clicking with Boateng in the second half.

Speaking at a news conference on Tuesday, Mustafi told reporters that he will "only focus on things which can be influenced."

"Training's a part of that," he said. "Everything else is down to the coach. I will be there if I am needed."

In his previous four tournaments as Germany's head coach, Joachim Low has never changed his starting formation going into the second group match.

Poland may be forced to make a change for the Group C clash after Szczesny picked up a thigh injury in the first half of Poland's 1-0 defeat of Northern Ireland on Sunday.

"It's a serious injury, but it gets better with every hour," assistant coach Bogdan Zajc said about the Arsenal keeper, who spent last season on loan at AS Roma.

Szczesny has been receiving medical treatment since Sunday and has missed the final training session ahead of Poland's trip to Paris.

"We need to have players with a 100 percent fitness," Zajc said. "If we are not sure, it's a chance for another keeper to play."

Swansea shot-stopper Lukasz Fabianski and Bournemouth's Artur Boruc could deputise for Szczesny, but Zajc did not reveal if a decision has already been made.

"I don't lead that discussion," he said. "We've got three world-class goalies."