Worcester have three loaned-out players hoping to do their parent club a favour against main Championship title rivals Bristol at Ashton Gate on Friday night.
Nottingham have been bolstered by the arrival of Warriors centre Heath Stevens and prop George Porter.
They supplement stand-off Tiff Eden, who arrived from Worcester last month.
Warriors, who currently lead the table by a point, will lose top spot if Bristol win - but can reclaim it by beating Plymouth on Saturday.
Nottingham go into Friday's game fourth in the Championship, but well adrift of the top two, who are so far ahead of the chasing pack they both booked their place in the all-important four-team end of season play-offs three weeks ago.
|It's tight at the top in the Championship|
|Worcester, who expect to have been dislodged from the top of the table by the time they run out at Plymouth Albion on Saturday afternoon, will be looking to extend their club-record winning sequence to 23 matches. Their only defeat was on the opening day of the season, at Ashton Gate, when they lost by a point to a converted Bristol try in added time. Bristol's defeat at Cornish Pirates on 1 February then allowed Worcester to claim top spot, courtesy of having achieved one more bonus-point victory.|
For Porter, it is a return to Nottingham, who he first joined on loan earlier in the season, playing in this season's first meeting between the teams, when they went down 27-13 in a tight game not settled until the final minutes, when a converted Bristol try cost them a losing bonus point.
He will begin his return on the bench, but there are places in the starting XV for both Eden and Stevens, who arrived from Plymouth Albion over the summer, but has missed much of the season with injury.
Worcester have already ruffled feathers at Bristol by signing two players from their main promotion rivals ahead of next season, winger Andy Short and scrum-half Luke Baldwin.
They have both since been loaned out by Bristol for the rest of the current campaign, Short joining London Irish and Baldwin moving temporarily to Bedford.