The magnificent Donbass Arena will resemble "a cauldron" when Manchester United enter Shakhtar Donetsk territory on Wednesday, according to their wily coach Mircea Lucescu. The 68-year-old veteran of 109 Champions League matches may have served warning to David Moyes but it was unnecessary. United's manager is discovering there are pitfalls everywhere en route to gaining acceptance after Sir Alex Ferguson.

Moyes's transfer acumen, coaching appointments and public pronouncements have all been questioned during United's worst start to a season for 24 years. Lucescu volunteered another factor before a Champions League meeting that, for the second midweek in succession, has Moyes needing a reaction from the Premier League champions – his rotation policy. With Rio Ferdinand absent, the result of a groin problem rather than poor performances against West Bromwich Albion and Manchester City, insisted Moyes, and Robin van Persie fit to start for the first time in four matches, it will be tested again in the coal-mining capital of Ukraine.

Lucescu spoke positively of Moyes and backed the United manager to overcome his early-season problems given that precious commodity of time but in identifying rotation as a cause of United's difficulties, he highlighted another area where Moyes is practically learning on the job. Rotation was rarely an issue in his 11 years at Everton, where resources were reflected in the thinness of his squad. Now it is a necessity with players he is still learning about and establishing a rapport with.

"There will always be a change of philosophy under a new coach and every coach needs time to work in a proper way," said the Romanian. "This is why David Moyes is facing difficulties at this stage. But we have analysed the United games and we noticed there are always changes in the squad, maybe four or five players [in each game].

"This rotation means the links between the players can be affected and I think turnover can cause a lot of problems sometimes. We have also discovered that here. The other big teams in the English championship, such as Chelsea, Liverpool and Arsenal, are not rotating the team as much as United and maybe that is a factor. We know the work of Mr Moyes from Everton and he is one of the strongest coaches in the Premier League. He needs some time to work with his players and let's hope the team finds a good pattern after tomorrow night."

Moyes would not be drawn into a rotation debate during his brief pre-match press conference at the Donbass Arena, although he did give Lucescu's words some credence by admitting he is on a learning curve with United's playing staff. "It never caused Sir Alex Ferguson any problems," said the United manager. "Manchester United always have had big squad of players and it's my job to use them and find out what is suitable. As I've said, I'm getting to know them much better."

On paper, this represents United's toughest assignment in the Champions League group stage but also an opportunity, for all their domestic issues, to take control of Group A. "Whether we win or lose the last game we always deal with it and move on," Michael Carrick said. "We've had a good start in this competition. It's a tough place to come but we're confident going into the game."

Shakhtar have won all three previous Champions League fixtures at home to English opposition – Arsenal twice and Chelsea last season – but are themselves in an inconsistent, transitional phase. Willian, Henrikh Mkhitaryan and Fernandinho have been sold in this calender year and the "Pitmen" stand third in a Ukrainian league they have won for the last four years. Their Brazilian influence remains strong, however, and in Douglas Costa, Alex Teixeira, Taison and Luiz Adriano, Shakhtar possess a forward line to capitalise on any United uncertainty.

"It will be like a cauldron in the stadium and our support will be very important," Lucescu said. "Champions League games are always a celebration for the city but ever since I have been the coach of Shakhtar we haven't faced the four top European teams – Manchester United, Liverpool, Real Madrid and Bayern Munich.

"We must show a very good performance against United because they are a very tough opponent. We have a different team from last season. It is one thing to lose one player and then lose a group of players, but we have lost a group. But we can still show our qualities against United and win."