Fowler's club, Liverpool, yesterday confirmed that the striker, who is suspended for the rest of the Premiership season because of a set-to involving Graeme Le Saux of Chelsea last month and some controversial line-sniffing celebrations in front of Everton fans at the Merseyside derby more recently, suffered a broken nose during a scuffle in the toilets of a Liverpool hotel early on Sunday morning.
Now the England coach Keegan, who is thought to be keen to name Fowler in the squad, must wait to see if the 24-year-old will be fit enough to travel to Budapest, although the striker seems likely to declare himself ready for action.
A Liverpool spokesman said: "He has seen medical staff and it has been confirmed that he has suffered a broken nose in the assault.
"We will have a clearer idea in the next couple of days what that means for treatment."
A spokesman for the Football Association, Steve Double, earlier said: "Obviously with every player who has the potential for England selection, we check around the time of selection if they are available.
"I would have thought that is the case with Fowler. We will be relying on the club's guidance."
If fit, Fowler could expect to play a key role in Budapest, with his club-mate Michael Owen and Blackburn's Chris Sutton both injured.
The incident, which occurred at Liverpool's Moat House Hotel, is the latest episode in a traumatic month for Fowler, following his much-publicised fine and six-match suspension as a result of the two cases of indiscipline.
Merseyside Police named the man charged with assaulting Fowler as 41- year-old Paul McCarthy, from Ellison Towers, in the Everton area of the city.
He has been bailed to appear before Liverpool City Magistrates' Court on 25 May.