Jose Mourinho's side have agreed a £75m deal with Everton for the Belgium international.
Hughes says it looks like Lukaku will be joining United despite Chelsea's interest.
Dier signed a five-year contract at Tottenham in September 2016.
Blues appear to have lost out to Manchester United in race to sign Lukaku.
Everton striker Lukaku is expected to officially join the Red Devils after Everton accept record offer.
Klaassen, 24, became Everton's second summer signing last month for around €27m (£23.6m, $30.8m).
Antonio Conte "fuming" after losing out on Belgium international to Manchester United.
Phil Neville believes Lukaku is a different type of striker from what United have had for a long time.
United have agreed a £75m fee with Everton for the transfer of Lukaku.
Merseysiders are under no pressure to sell and say reports that a bid has been accepted are "premature".
Wayne Rooney and Alvaro Morata's future could be affected by Lukaku's move to Old Trafford.
Lukaku seemingly preferred a move to Chelsea.
The Belgium international is wanted by Chelsea manager Antonio Conte.
Conte wants Chelsea to sign Lukaku, even if the striker will cost them £100m.
Lukaku has scored 25 goals in the league last season.
Lukaku hoping for a move back to Stamford Bridge.
Lukaku is keen to leave Everton after four years with the club.
Tony Cascarino says champions should be looking beyond Lukaku as a summer replacement for Diego Costa.
Lukaku recently said staying at Goodison Park is 'not an option' for him.
Everton are keen to retain the services of Lukaku and will demand £90m for the striker.
Jorgensen scored 25 goals in all competitions last season for Feyenoord.
Lukaku is keen to play in the Champions League and has asked to leave Everton.