David De Gea's new Manchester United contract is set to keep him at Old Trafford for the next six years, sources have told ESPN FC.

The Spaniard is expected to pen his new deal, worth more than £110 million, before the start of the season to bring an end to 18 months of talks.

Sources told ESPN FC the goalkeeper, rated as one of the best in the world, has been given assurances that United remain committed to challenging for the Premier League and Champions League after a sixth-place finish last season saw Ole Gunnar Solskjaer's side forced to settle for a place in the Europe League.

His new contract will keep him at the club until he is 34 and he will be eligible for a testimonial in two years after moving to Old Trafford from Atletico Madrid in 2011.

Sources also told ESPN FC one of the reasons behind his decision to stay at United, shunning interest from Juventus and Paris Saint-Germain, was the support he received from Solskjaer during a disastrous end to the season.

A series of high profile mistakes, including a terrible gaffe in the 3-0 defeat to Barcelona at Camp Nou in April, hit his confidence, but despite calls for the 28-year-old to be dropped he kept his place -- a gesture appreciated by De Gea.

Confidence over De Gea's new deal should mean that Dean Henderson is allowed to return to Sheffield United on loan.

The England Under-21 goalkeeper, who has attracted interest from Bayern Munich, spent last season at Bramall Lane and manager Chris Wilder is keen to have him for their first season back in the Premier League following promotion in May.

Henderson is in negotiations over a new contract and sources have told ESPN FC that after fresh talks in London last week there is confidence on both sides the 22-year-old will sign a new deal before heading back to Sheffield United.