The Great Britain international stand-off has been a revelation since crossing the Pennines. His personal form and his ability to bring others into the game have been major factors in Leeds' climb up the Super League table, where they now stand second to Bradford, albeit seven points behind.
The Warrington coach, Darryl Van de Velde, admits to wondering whether he could have retained a player he greatly admires had he arrived at the club a couple of weeks earlier.
As it was, Harris was past the point of no return and Van de Velde has since used a variety of players in the stand-off role, none of whom has handled it with the aplomb Harris has shown at Leeds.
Wigan will still be without Terry O'Connor against Paris St-Germain in one of the three other Super League matches tonight. Their coach, Eric Hughes, retains the side that beat St Helens this week.
Saints, meanwhile, will be without both Andy Northey and Ian Pickavance for Sunday's trip to Halifax. Pickavance has been suspended for one match after his sending-off against Salford last week, while Northey has failed in his appeal against a four-match ban for using his knees in a tackle on London's Martin Offiah.