Once when Roy Keane and El Hadji Diouf looked at each other, it was with menace in their eyes. Competitive, combustible and controversial, each recognised something familiar in the other and did not like it too much. Not until last week, though, did we discover those glares also included admiration.
But Keane's £3.5m offering to Bolton for Diouf revealed the Irishman's true view, and yesterday we were given the African's. It was not long into their meeting, Diouf said, before the two spoke of past confrontations: "We talked about that quickly – he [Keane] is not too old to forget that."
The League Cup final of 2003, when Liverpool beat Manchester United 2-0 in Cardiff, remains fresh in Diouf's mind. "I had words with him. We also had an argument in a league game at Liverpool when we lost 2-1.
"Everybody knows Roy Keane as a temperamental man, and they know me like that as well. I am similar to Roy Keane because he used to be a bad loser as well. I hate losing, just like he did, he was always so hot on the pitch. I am like that as well. People used to boo Roy Keane wherever he went and now they do that to me. But people never boo a bad player."
At 27, and with six seasons behind him at Liverpool and Bolton, Diouf has the Premier League pedigree Keane knows Sunderland need if they are to progress from last season's 15th place.
Bolton finished 16th, thanks largely to Diouf's opener at home to Sunderland in the penultimate game of the season.
Predictably given Diouf's spit and spat-filled past, he was abused by the travelling Wearsiders, the same fans who clapped him on to Nottingham Forest's pitch on Wednesday night.
"I know that opposition supporters like to hate me," Diouf said, "but I am totally comfortable with that. I like to wind the opposition up. If I know people are ready to boo me, I want to score against them. I know the Sunderland supporters will support me.
"I chose Sunderland ahead of both Portsmouth and Paris St-Germain because I came here and saw the training facilities and the stadium.
"It's beautiful. I know what this club is capable of. It's a long time since Sunderland have played European football, but why should it not be possible? If Bolton can do it, why shouldn't Sunderland?"
The arrivals of Diouf and Steed Malbranque prompted Ross Wallace to leave for Preston North End yesterday on a season-long loan.