Shakhtar Donetsk manager Mircea Lucescu believes David Moyes has unsettled Manchester United with his constant tinkering.
Moyes, who replaced long-standing manager Sir Alex Ferguson in the summer, has guided Manchester United to their worst start to a league campaign in 24 years.
They go in to their tie against the Ukrainian champions tomorrow night on the back of a shock home defeat to West Brom and Lucescu believes Moyes is to blame for their poor form.
"You can always see four or five new players and, because of this rotation, the links between players are not always very good. Turnover creates a lot of problems for them.
Moyes made seven changes from the team that lost 4-1 to Manchester City against West Brom, which they again lost in a 2-1 defeat. That was the third defeat in six games for the Premier League champions, leaving them 12th, eight points off leaders Arsenal.
Lucescu believes his consistent squad choices gives them the edge in the match but has backed Moyes to improve if given time to succeed at Old Trafford .
"In the Ukrainian championship we are not rotating the squad as much as United, so maybe that is why we have been more secure," he said.
"Of course, we know the work of Moyes at Everton. Anyway, he needs time to share some ideas with the players. Carlo Ancelotti has some problems taking over from Jose Mourinho at Real Madrid and Manuel Pellegrini is the same at Manchester City.
"You need some time to prepare the team. Lets hope they find it - but only after tomorrow’s game."