After missing from Manchester United's list of players to be retained for the upcoming season, David de Gea's future at the club is once again in doubt.

The list, which was made public on Friday and including Mason Greenwood, comprises both players with existing contracts at Old Trafford and those who have been extended new offers.

De Gea's exclusion indicates that the current £375,000-per-week contract's replacement talks are not as far along as once believed, and insiders indicated that United are no longer as certain that the 32-year-old will stay.

Discussions with David over a potential new contract remain open, according to a brief club statement.

On June 30, when his current contract expires, De Gea will be free to leave Old Trafford completing the a 12-year a tenure track at United.