The QPR manager is aware of the danger the two attackers pose having worked with them when they were all at Fulham while he was in charge at Craven Cottage in 2010-11.
Hughes and the attacking duo worked together in 2010 when the Welshman was in charge at Craven Cottage, and even with all three of them leaving Fulham, Hughes is still aware of the threat that both players will pose to his side.
The former Manchester City manager told reporters, "I've got huge regard for Mousa. He is an outstanding football player and now he is at a club which, and this is no disrespect to Fulham, has a higher profile and is getting a lot more attention. But he was still producing what people have seen in a short period of time, week in, week out for me and Martin Jol when I left.
"He is an outstanding footballer and I always knew when he came to the Premier League that he would make an immediate impact. He certainly has done that.
"He is technically very, very accomplished. He is able to play in a number of positions: he can play off the front, right up top, he can play in midfield, he can play in wide positions. That's the quality of the player that we are talking about.
"I knew almost immediately when he went to Tottenham that he would enjoy it and be able to fit in very, very quickly, because he is an outstanding football player."
While Hughes was in charge at Fulham when Dembele came to the Premier League, he has also identified Dempsey as a threat to QPR on Sunday.
"Clint is a very single-minded young man and he is a guy that is very, very driven. He wants to progress in his career and he does everything to that end. He works exceptionally hard in training, had an outstanding season obviously when I was manager and probably topped that with the amount of goals he scored for Fulham last year.
"You probably felt it was the right time for him to move. He was at the peak of his powers and he wanted to move on to pastures new."