Marouane Fellaini has become the great conundrum for the Manchester United disciple. As virtually the last man standing on the club's transfer target list, bar-room and Twitter debate centres on whether the midfielder is precisely what the David Moyes project needs.

As the Scot watched his side play out a goalless draw with Chelsea on Monday evening at Old Trafford, a vision of the bushy-haired Belgian surely presented itself.

The player most likely to be Moyes's first – and perhaps only – major signing before the window closes has the potential to offer United a rare dimension: Fellaini is the 6ft 5in powerhouse whose dynamism and presence could bust games open from a withdrawn or advanced central berth.

However, the caveat here is "potential". A rawness remains despite five years in the Premier League that caused Moyes's hesitation before last week's £28m joint bid to Everton for Fellaini and Leighton Baines. The great unknown is how the Belgian may prosper in the harsh glare of being a United player, an issue for any footballer when signing on at the Theatre of Dreams.

With Michael Carrick gluing the midfield together and Tom Cleverley toiling further ahead, the lone United spark against José Mourinho's striker-less Chelsea came from a zestful Wayne Rooney.

While the unsettled forward turned in an impressive display against the club he wants to join, dropping in and out of midfield, the contest still meandered. Despite the attacking forces of Rooney, Robin van Persie, Danny Welbeck and Antonio Valencia the creation of chances was stymied by a visiting rear-guard marshalled expertly by John Terry. On the bench Moyes's match-changing options extended to Shinji Kagawa, Ryan Giggs and little else. The Japanese was ignored, and only 12 minutes remained when the Welshman was thrown on, and Giggs's entrance was to steady, rather than change, proceedings.

To be able to place Fellaini alongside Carrick to steal a goal from midfield – the Belgian scored 13 to Cleverley's four last season – or have him as a kind of giant No10 to offer an aerial threat missing from United are the central motivations behind Moyes's pursuit.

The grand United tradition does not countenance lump-it-up football, of course, so a fear may arise that Fellaini's arrival would signal a more agricultural approach from the new manager. Yet this seems unlikely given the talent at Moyes's disposal and his determination to continue an attacking lineage that runs from Sir Matt Busby to Sir Alex Ferguson.

Fellaini would provide one more option for the shrewd 50-year-old, who in the display drawn from Rooney illustrated his cleverness as an operator. The points were shared with Chelsea, but the big winners were United and the forward, as Moyes's man-management of Rooney paid off.

A player who is "angry" and "confused" was still able to steal the show, orchestrating the match in a performance that illustrated why Moyes wants to keep him, and Mourinho is keen to make him the main Chelsea man.

In the type of stalemate written up as not being "a great advert for the English game" Rooney shone in a first United start since 28 April, when he lasted 88 minutes before Ferguson replaced him during a 1-1 draw at Arsenal. The last time Rooney played a full game was the 2-0 win at Stoke City on 14 April, when he was fielded out of position in midfield.

Yet now, the standing ovation Rooney received towards the end against Chelsea could prove the first of many this season. A campaign that ends in Brazil at next summer's World Cup – if England qualify – should keep the personal motivation fuelled if he is confirmed as a United player once 2 September passes.

Moyes said: "I was very pleased with Wayne's performance and very pleased by the reaction from the crowd. That wasn't unexpected – I expected it. I told him I might only play him for 60 or 70 minutes and see how he was. But he worked back, he tackled and he was great. He closed two or three people down in the corner and the crowd realised the work he did. He was desperate to score and nearly scored with an overhead kick in injury time.

"He's been great in training and anyone who has looked at him has seen a slightly leaner Wayne. I think Wayne has a positive mind at the moment. I don't think that needs to change. I think his attitude showed a lot tonight."

Mourinho was left sounding defeated in his pursuit of Rooney, informing him he had 48 hours to hand in a transfer request or Chelsea's interest was over. For Moyes that moment cannot arrive quickly enough.

If Rooney is still at Old Trafford by next Tuesday, it will feel like the signing of a new player. By then Moyes hopes Fellaini has also joined to finally strengthen the squad.