By Simon Austin and Mark Jolly BBC Sport at Queen's

Henman has struggled to impose himself in the early rounds Friday's order of play

Things get serious at Queen's on Friday as some of the game's biggest names come head-to-head in the quarter-finals.

The top players spent the first few days honing their grasscourt games following a hard clay-court season, but now the final prize is in sight.

Tim Henman has looked unconvincing in his first couple of games, struggling with his serve-volley game and blaming the courts for being too slow.

He had to rely on a deciding-set tiebreak to see off Davide Sanguinetti in the second round and was then taken to three sets by Cyril Saulnier in the next round.

The British number one looks to have the easiest draw in the quarters - an encounter with little-known Frenchman Anthony Dupuis.

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But Henman is refusing to take anything for granted against a player who has put out 16th seed Wayne Arthurs and Briton Alex Bogdanovic.

"I played him in Basle a couple of years ago and he plays very similarly to Saulnier," Henman said.

"He is a shot-maker and likes to give the ball a crack.

"I'd like something a little more straightforward than today but he's come through a couple of tough games and I know I've got to play well to beat him."

He's a tough competitor, moves well and he knows his way round a grass court Hewitt on Grosjean

Top seed Lleyton Hewitt has also struggled in the first couple of rounds.

He had to draw on all his trademark fighting spirit to see off dashing Dutchman Raemon Sluiter and giant Belgian Dick Norman.

The diminutive Australian is first on Centre Court against sixth seed Sebastien Grosjean of France.

In contrast to Hewitt, Grosjean has negotiated his first two matches with the minimum of fuss.

Hewitt admitted: "It's going to be another tough match. I've only played him once before on grass, in the Davis Cup, and I got him then.

"He's a tough competitor, moves well and he knows his way round a grass court."

Roddick's serve is one of the fastest in the game

Andre Agassi, who looked in imperious form as he demolished 1996 Wimbledon champion Richard Krajicek in the third round, faces Xavier Malisse.

The talented Belgian reached the semi-finals at Wimbledon last year and should provide Agassi with his toughest test of the tournament so far.

The final quarter-final on Centre Court puts two of America's brightest new stars head-to-head.

Taylor Dent and Andy Roddick are both charismatic big-hitters who have impressed hugely at Queen's this year.

Roddick admits Dent could have the advantage because he is more naturally suited to grass.

"He feels more comfortable on the surface than me," said Roddick, who put out Britain's Greg Rusedski in the third round.