Would Alan Shearer, ruled out on Saturday, be ready to return? Would Duncan Ferguson, now close to fitness, play any part? Did he know which team he would like to put out at Old Trafford next Sunday? Would he be keeping any secrets today?
"No. No secrets," he said. "I won't be playing any mind games with George Graham. I will not be trying to hide things."
Were the Tottenham manager to try to elicit Gullit's first-choice semi- final line-up, however, he would be disappointed. Gullit, apparently, doesn't even know it himself yet.
"I don't have a team in mind," Gullit said. "It depends on form. We played well today, offensively, but you are influenced also by what happens in training as well as in matches."
Newcastle were in training yesterday, with Shearer and Ferguson involved. But to questions over what part they might play today Ruud would say no more than "we shall see". And there the matter was left.
The truth, one suspects, is that Gullit is a manager with a difficult choice to make. He had just witnessed perhaps Newcastle's most incisive attacking performance under his charge (forget the defending, for the moment) yet will surely have been planning to restore Shearer and Dietmar Hamann (nursing minor injuries on Saturday) to the starting eleven and seems to have Ferguson - out since January - to a semi-final schedule. To change or not to change a winning side: the classic manager's headache.
And on this occasion a subject about which the man hiding nothing would reveal very little.
His inquisitors did try. "Was this the way he wanted his team to play?" someone asked, having listened to Gullit's fulsome praise of the way Temuri Ketsbaia, Silvio Maric and Nolberto Solano had combined in rapid inter- plays at Pride Park and knowing full well that with Ferguson on board - even Shearer, to a lesser degree - the style would have to change.
"There is not one way I want to play, not one ideal," Gullit countered, side-stepping as neatly as in his playing days. "It depends on the opposition, on the occasion." But would he be happy to play this team in the semi- final? "Yes, I would," he said. Aha. Progress...
"But we shall see. Let's just celebrate a victory today, shall we."
It was worth celebrating, too, after 90 minutes of breathtaking entertainment in which Derby, as vibrant in attack and accident prone in defence as their opponents, twice led and twice gave away their advantage before Newcastle finally imposed themselves when Solano volleyed home the goal of the afternoon.
Derby, inspired at first by Francesco Baiano's outstanding form, might have won the day themselves with better luck. Deflections played a part in two of the goals they conceded - crucially in Ketsbaia's case - while only a brilliant save by Shay Given from Mikkel Beck denied them a 3-2 lead. What's more, as Jim Smith pointed out, another referee might have shown Nikos Dabizas a red card for the shirt pull on Baiano that gave Derby their penalty.
But Newcastle, driven with great purpose by Rob Lee and Gary Speed in midfield, were buzzing, not least, one imagined, because of the doubts cast by Smith over their eligibility for next season's Uefa Cup, their participation in which, it was confirmed last week, is almost guaranteed by their FA Cup semi-final appearance, win or lose. The idea that Derby might qualify by finishing fifth in the Premiership has been knocked on the head.
"I could tell that they were up for the game," Gullit said. "Offensively, we gave an excellent performance. We were not happy about our defending and as a coach it is my duty to point out the mistakes. But overall I am a happy coach."
Happy... but not sure, it seems, about what to do next.
Goals: Burton (8) 1-0; Speed (11) 1-1; Baiano (pen 22) 2-1; Speed (24) 2-2; Ketsbaia (39) 2-3; Solano (60) 2-4; Wanchope (90) 3-4.
Derby County (3-4-1-2): Hoult; Prior, Carbonari (Wanchope, 65), Laursen; Borbokis, Bohinen, Schnoor (Sturridge, 82), Dorigo; Baiano; Burton, Beck. Substitutes not used: Poom (gk), Harper, Murray.
Newcastle United (4-4-2): Given; Hughes, Charvet, Dabizas, Griffin; Solano (Brady, 65), Lee, Speed, Domi; Ketsbaia, Maric (Saha, 79). Substitutes not used: Harper (gk), Caldwell, Andersson.
Referee: D Gallagher (Banbury).
Bookings: Derby: Prior, Burton. Newcastle: Dabizas.
Man of the match: Lee.