Aston Villa manager Martin O'Neill believes Guus Hiddink would find it difficult to manage both Russia and Chelsea on a permanent basis.
Hiddink has taken charge of the Blues until the end of the season while continuing to plot Russia's bid to reach the 2010 World Cup finals. There has been speculation that Hiddink may also continue at Stamford Bridge long term but O'Neill has doubts over whether it would be possible to combine the two roles.
He said: "The dual role is incredibly hard. I think there might be a reason for doing it on a short-term basis (at Chelsea). But overall, I think it would be very hard to combine an international management role with one in the Premier League over the fullness of time."
He added: "I'm not sure that's what they are looking at (at Chelsea). Eventually - when you lose a game or two - someone will accuse you of not spending enough time in one particular camp.
"I think it is exceptionally difficult. Nothing is impossible. Over a short period of time, I'm sure it could work but over a three or four-year period, I think that would be particularly difficult."
Hiddink watched Villa draw 1-1 with CSKA Moscow in Wednesday's UEFA Cup tie ahead of Saturday's Barclays Premier League clash at Villa Park.
Villa would go five points clear of fourth-placed Chelsea if they can avenge a 2-0 defeat at Stamford Bridge earlier in the season.
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