The idiosyncratic Northern Irishmen who spent two fruitful years together at Rugby Park, masterminding one League Cup win and a couple of top-six near misses, will be reunited across the technical areas at Cappielow on Saturday when Morton play host to Cowdenbeath in the Championship. With the Fifers hoping to extend the Greenock side's deficit on the remainder of the division to 12 points, not to mention save themselves from the ordeal of the play-offs, the match has all the makings of a relegation six-pointer and the sparring between these two countrymen has started early.
"I am going to wind him up," Shiels mischievously tells Herald Sport. "You are not allowed to be at three clubs in the one season so I think we should put in a protest. Tell Jimmy I am going to investigate that, because he has been at Kilmarnock, Hibs and now Cowdenbeath."
"Only three in a year?" replies Nicholl. "That is a record for me!"
All joking aside, while these two weren't exactly hewn from the same cloth - Shiels was idealistic, Nicholl more pragamatic - they forged a formidable alliance. While Shiels and his predecessor Mixu Paatelainen tend to receive most of the credit for instilling the fluid, short, passing game which won so many plaudits, results were every bit as good on the occasions where the manager was serving out a suspension in the stand and Nicholl was at the controls.
In their own ways, both men have continued to produce - Cowdenbeath have conjured wins against Dundee, Hamilton and Raith Rovers since replacing Colin Cameron late last year, while Shiels' Morton have recovered sufficiently to go into the match on a four-game unbeaten run. Suffice to say both could also do with the points on Saturday.
"I don't think he had as much covering to do as Maurice Malpas, Johan Mjallby or Tommy Wright" insists Shiels. "The managers of those clubs have been suspended much more than me, I only had three offences in my two years, it is exaggerated. But Jimmy was a really good assistant to me, he worked tremendously hard, and Kilmarnock was a great chapter in my life," he added. "Jimmy worked with me for two seasons and they were two remarkable seasons. There was no secret: we just got on well and worked hard together - that is the recipe for any successful sporting team, sportsperson or individual in life."
With the lucre of matches against Rangers and Hearts in next year's Championship focusing minds, there is a feeling that Morton have most at stake, but Shiels typically puts an alternative spin on things.
"We haven't given up hope," says a man who was clearing snow from the club's Parklea training ground yesterday morning. "We never give up hope. But we are not going to apply extra pressure to the players by saying we have to win. What people are forgetting is that there is a lot of pressure on Cowdenbeath's players as well. They have got themselves in a position where a draw is no good to them, because they need to keep themselves away from the end-of-season trauma of the play-offs, whereas people are saying we are nailed on to go down. They are hot favourites for this game on current form."
The bluff and counter bluff between two men who know each other inside out might be instructive - could, for instance, Shiels abandon his favoured passing game and go for the curve ball of agricultural punts to Garry O'Connor? These conflicts and coincidences occur regularly in Scottish football yet Nicholl has yet to feel the benefit of the inside track. In his last spell at Cowdenbeath, he came off second best when he met another old pal in Jimmy Calderwood at Ross County a few seasons ago.
"If I had any input at all during the two years it was just to try to say that we are in a precarious position here, say we were getting beaten 1-0, but [Kenny] stuck to his guns, said 'no this is the way it is going to be'," says Nicholl. "He could change his mind and come up with something I don't expect him to come up with, but I don't know . . . Even if we beat them and it is 12 points that won't be enough. Only when we are mathematically safe - and when I say safe I mean out of the play-off place - will I be happy."
There is another meeting between the two, this time at Central Park, still to come this season, and win, lose or draw the two men will share a glass afterwards. "I hope his fridge is full," says Nicholl.