"You don't need any more motivation than the fact it's a home European Cup game, there is added spice to it with the fact they have already beaten us this season.
"We don't like to be beaten home or away by too many teams, so that adds a little extra importance for us. We want to beat them.
"There are some harsh lessons to be learned from this European campaign - if we can grow and stay mentally strong and if it makes us a stronger squad then we can build into next season."
Harlequins top Pool 4 with four successive wins, although they have notably lost their last two Guinness Premiership games.
Ulster skipper Best knows that 'Quins will be coming to Belfast looking to copperfasten their qualification for the Heineken Cup's last-eight.
"Whenever you look at teams you have to look at a squad as a whole, and for Harlequins to make a big name signing like Nick Evans in the summer, and then to be without him for three months, and still go on the run they did without him tells you what they are like as a squad.
"Now Evans is back, it makes them even stronger again. They are a very good team, with some very good players.
"When you look at England's performance in the autumn, their stand-out players over the series were a lot of the 'Quins players.
"They are similar to us in that they are a young squad, so they will come here with maybe not the same fears that a more experienced team would come with, and in many ways that makes them a lot more dangerous.
"It will be a really tough match. We are not going into it thinking we have nothing to lose, we are going in to it thinking we have everything to play for and we will make it a hard game for them."
The Ireland hooker added: "There is a real buzz at training and a great positive attitude with the boys - we aim to bring this with us to the very end of our Heineken Cup campaign.
"I really hope that the Ulster supporters come out for the game and that we can make them proud."
Tickets for the Ulster v Harlequins match can be purchased online by clicking here, from the Ravenhill Ticket Office at the counter or on the phone on tel: 028 9049 3222 (Option 2) or from one of the below Ulster Rugby ticket outlets.
In Sport, 15 Frances Street, Newtownards
SS Moores 6 Chichester Street, Belfast
Athletic Stores, 41 Queen Street, Belfast
Eden Park, 613 Lisburn Road, Belfast
Euro Sport, 84 Antrim Street, Lisburn
Donaghy's Sports, 25-31 Newry Street, Banbridge
Style N Sport, 20 Church Street, Ballymena
Podium 4 Sport, 40 Montgomery Road, Belfast
Overplay Sports, Unit 4, Keeburn Industrial Estate, Woodburn Road, Carrickfergus (opp Carrick Rugby Club)
Douglas Menswear, Unit 8, Bedford House, Bedford Street, Belfast
Game On, 31 High Street, Portadown, BT62 1HP