Ulster opened up a three-point lead in the Celtic League with a 24-17 victory over Newport-Gwent Dragons at Ravenhill yesterday.
Bryn Cunningham, Tommy Bowe and David Humphreys touched down for Ulster with Humphreys adding three conversions and a penalty. Steve Jones and Hal Luscombe went over for the visitors and Craig Warlow kicked the rest of their points.
The day's other scheduled Celtic League fixture, between Llanelli and Munster at Stradey Park, was posponed because of a waterlogged pitch. Meanwhile, the Scotland No 8 Simon Taylor will miss Edinburgh's trip to the Ospreys today due to a back injury.
Leeds, seven points adrift of 11th-placed Saracens, begin a five-match quest for Guinness Premiership survival when they visit the champions, Wasps, today.
After hosting Saracens at Headingley on Friday night, they then travel to London Irish and host Gloucester before completing their league programme at Newcastle on 6 May. Leeds welcome back their Scotland internationals Gordon Ross and Gavin Kerr, and call up prop Rayno Gerber, hooker Rob Rawlinson and flanker Dan Hyde.
Wasps include Josh Lewsey, Mark van Gisbergen and Joe Worsley, who all agreed new club contracts earlier this week.
Saracens, hosts to Worcester today, have made one change from the side who recently beat Sale 15-9, with prop Kevin Yates replacing Nick Lloyd. Worcester, buoyed by a victory over Wasps, welcome back their captain, Pat Sanderson, who has not played since January due to a back injury.
The England centre Jamie Noon will sit out Newcastle's Kingston Park clash against Northampton because he is still recovering from the blow he suffered to his head against Ireland last weekend.
Northampton, one place below Newcastle in eighth, have named their England duo Ben Cohen and Steve Thompson, and the full-back Bruce Reihana makes his 100th appearance in Saints colours.
In National League One, Bedford pulled to within eight points of leaders Harlequins with a 34-28 home successs over Plymouth Albion. But Quins visit Cornish Pirates today.
In the Super 14, Highlanders shaded South Africa's Cats 16-14 in Invercargill while Western Force lost 30-21 in Perth to the Bulls.