Chinnor director of rugby Lynn Evans has warned his players they face a banana skin when they visit Cleve in South West 1 tomorrow.
Having disposed of Bracknell last week to take over top spot, Chinnor will be high on confidence.
But Cleve have also made a strong start to the season and will be smarting after their 55-13 defeat at Weston-super-Mare.
Evans said: "This game is a banana skin for us. It is easy to slip up after such a good effort against Bracknell.
"If we are going to win this league, we have got to be up for every game.
"We don't want to throw away our advantage.
"We do need to score some points as well as we have a worse points difference than Bracknell.
"That means scoring more tries."
Pat Stenning returns at hooker in place of Alan Cawston, while Pip Seymour should replace Sam Portland (broken leg) on the wing.
Zane Winslade is likely to move to No 8 as Harry Jackman is injured with Adam Hastings coming at flanker.
Captain Matt Hutchings hopes to be fit, but Andy Millburn is on standby.
Highly-rated Australian Mark Preston makes his debut for Oxford Harlequins when they host St Ives (2.30pm).
Preston joins from Sydney club Gordon, the former team of Quins' centre Beau Wilson.
The fly half or full back recently came runner-up for the Ken Catchpole Medal - Sydney club rugby's biggest individual honour.
Quins may have another debutant in prop Nick Goodger, a former Leicester Lions player, who has recently impressed at Banbury.
Goodger is vying with Ed Mitchell for the loose-head position as Chris Aldous is unavailable.
Lock Adam Pearson (ankle) remains doubtful, while flanker Chris Alcock will look to force his way back into the starting line-up.
Henley Hawks finally hope to have flanker Matt Payne back for tomorrow's clash with National 2 leaders Manchester at Dry Leas.
The influential No 6 has been out with an ankle problem in recent weeks, but he could now return at just the right time as his replacement Steve Green has a knee injury.
Back Danny Wells may be available if he has recovered from his thigh injury.
Centre Angelo Flammia will be considered for a place on the bench after a lively performance for Henley Alliance at Newbury.
Unlike Henley, Manchester have been largely injury free and have already scored 28 tries.
Their back line features England Sevens player Andre Vilk, who is on loan from Sale Sharks.
Captain Jez Hicks moves to blindside flanker as Witney host Newbury Stags in Southern Counties North.
Alan Richens comes in at lock, while Carl Campbell moves from No 7 to No 8.
Hooker Adam Copperwheat deposes Charlie Quarterman and Andy Gosling replaces Mark Serle at prop.
Bicester will bid to inflict Drifters' first defeat of the BB&O Premier Division season.
Drifters have seven matches out of seven so far, but have scored 46 points less than third-placed Bicester.
The hosts will be without John Rollason and Chris Nash who are both away.
Back row Martin Linstrom is out with an eye injury, while wing Leigh Robinson has a hamstring problem.
Henley Hawks (v Manchester, home): from Le Chevalier, Fuller, Muggridge, Alexipoulos, Robinson, Beech, Winterbottom, Hurrell, Chamberlain, M Payne, Williams (capt), Archer, N Lambden, Ah-Ling, Wells, L Burns, Reeves, Flammia, Meehan, Gaunt, Simmons.
Chinnor (v Cleve, away): from B Hewitt, Seymour, Williams, Powell, Carter, Cathcart, Gustafson, Winpenny, Stenning, Whelan, Harris, Hutchings (capt), Burrows, McGuire, Hastings, Winslade, Millburn, Harding.
Oxford Harlequins (v St Ives, home, meet 12.45pm) from Mitchell, Needham, DeLange, Goodger, Eckert, Payne, Pearson, Alcock, Gerber, Soper, Rowe, A Cope (capt), F Jones, Noyce, A Henley, Wilson, Johnson, Davies, Preston, Lafayeedney.
Witney (v Newbury Stags, home): Wheater, P Gouldie, Rollinson, Ellwood, C Strutt, H Lamb, G Campbell, Dore, A Copperwheat, Gosling, Fowler, Richens, J Hicks (capt), Muller, C Campbell. Reps: Serle, C Quarterman, Monks.
Bicester (v Drifters, home): A Morris, Rakacikaci, Lewis, A Spencer, Walsh, R Kenny, Risbridger (capt), Shaw, Davies, Barnes, Malins, W Morris, Nightingale, D Spencer, Thurlow. Reps: N Kenny, Giles, A Willmore.
Oxford Harlequins 2nd (v Reading Redingensians 2nd, away, meet Southern Bypass, 12.30).
Oxford Harlequins 3rd (v Tadley 2nd, away, meet Southern Bypass, 12.30).
Oxford Harlequins 4th (v Thatcham 2nd, away, meet Southern Bypass, 12.30).
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