Shakhtar Donetsk coach Mircea Lucescu says Manchester United's poor form means nothing ahead of Tuesday's clash at Old Trafford.
David Moyes has been under increasing pressure with United suffering two straight losses to slip to ninth in the English Premier League.
But Moyes' men top Group A in the UEFA Champions League and Lucescu warned his team United were a different prospect in European competition.
"Even though they are not playing well, these are two different competitions and you can't really compare them," he said.
"In the Premier League, the English teams know each other and the teams they are playing, but with the Champions League it is a totally different situation.
"For Manchester United it is a must-win match as they want to win so they can top the group and for our part we are going to play our best as it is important for us to progress as well."
Lucescu expects Moyes to rotate his squad with an eye to Sunday's Premier League trip to Aston Villa, but said even then United were a strong side.
"Every manager knows their squad back to front and each individual player, and each manager has his own style," he said.
"Some prefer to rotate to keep the squad fresh and some prefer to keep the same team.
"In David Moyes' case he likes to rotate his team but the squad is very strong and therefore the quality of the players doesn't diminish."
United suffered a 1-0 loss at home to Everton on Wednesday before slumping to a 1-0 defeat against Newcastle at Old Trafford on Saturday.
Lucescu noticed United had 'lost their spark' against Newcastle, but believes they were still close to taking something out of the clash.
"When they were playing Everton it was David Moyes' former team so they were playing with special enthusiasm and motivation, but when they played Newcastle it was like they had lost their spark a bit," he said.
"The result of the game does depend on some small things, though. For example, if they got a penalty for the handball against Newcastle, it could have been completely different."
|Coach: D. Moyes|
for A. Young 63'
for R. Giggs 63'
for A. Büttner 88'
|Messi has ´no problem´ with Luis Enrique|
|Relegated Tranmere appoint Brabin|
|Ujah agrees Werder transfer|
|Magath backs Guardiola to remain at Bayern|
|Mathieu out of Bayern clash|
|Burnley appeal Duff dismissal|
|Setif drawn in Algeria-heavy Champions League group|
|Terry calls for new Drogba deal|
|Saul agrees bumper Atletico deal|
|Arsenal need to finish season strongly - Wenger|
|New Bilbao deal for Gurpegi|
|Terry: Too long between titles|
|Pepe puts Morata friendship aside for Champions League match-up|
|Hazard can be as good as Messi, Ronaldo - Fabregas|
|Carlisle ´deeply ashamed´ about suicide attempt|
|Tevez planning to win Champions League with Juve|
|Blatter ´knows absolutely nothing´ - Maradona|
|Allegri: Ancelotti a smart man|
|Sunderland academy coach to manage Oldham|
|Primeira Liga Review: Braga secure Europa League berth|
|Bruce backing Hull to respond against Burnley|
|Almeria 2 Celta Vigo 2: Bifouma, Zongo inspire hosts´ comeback|
|Arsenal can mount title bid - Wenger|
|Turkish Super Lig Review: Besiktas and Galatasaray remain locked at the top|
|Cagliari 4 Parma 0: Festa revival back in gear|
|Hull City 1 Arsenal 3: Sanchez at the double as visitors close on second|
|Blackpool - Huddersfield game will not be finished|
|Allegri vindicated by Juventus success|
|Russian Premier League Review: Krasnodar close the gap as Zenit slip up|
|Al Ahly dismiss Garrido|
|MLS Preview: Kinnear returns to Dynamo with Earthquakes|
|Ancelotti all out for victory against Juventus|
|Ramires recovering well after sickness|
|Prince Ali would back rival FIFA candidate to oust Blatter|
|Barcelona v Bayern Munich: Guardiola makes Camp Nou return|
|Kruse a target for Wolfsburg - Allofs|
|Fletcher backing Bournemouth to ´surprise a few´|
|Bremen agree deal with Fritz|
|Carver gets Newcastle backing|
|Blaszczykowski suffers groin tear|
|Boateng warns of Barca ´storm´|
|Brouwers agrees Gladbach extension|
|Benzema to miss Turin trip|
|England great Jimmy Greaves suffers stroke|
|Cabaye concerned by bit-part role at PSG|
|Parry: Anfield expansion a major boost|
|Ki targets Arsenal win and seventh spot|
|Pirlo eyes potential Champions League swansong|
|Mourinho rounds on critics after clinching title|
|Henderson: Liverpool can push on without Gerrard|
|Lack of goals a concern for Van Gaal|
|Hard to keep Benteke - Bacuna|
|MLS Review: Sporting KC end Chicago streak, Martins brace furthers NYC pain|
|Copa Libertadores Preview: River eye revenge in Superclasico|
|Garcia lauds ´impressive´ Roma|
|Pavon goal scores him a BMW for a month|
|Boca beat River in Superclasico|
|Inzaghi to blood youth after third straight Milan defeat|
|Blanc urges PSG to ´remain vigilant´|
|La Liga Review: Valencia go clear of Sevilla, crisis-stricken Elche safe|
|CAF Champions League Review: ES Tunis dumped out by Al Merreikh|
|Masterful Mourinho has Premier League and Chelsea singing his tune|
|Nantes 0 Paris Saint-Germain 2: Cavani nets again as Ibrahimovic returns|
|Napoli 3 Milan 0: Late treble saves hosts|
|Primeira Liga Review: Porto edge past strugglers Vitoria|
|Bundesliga Review: Hamburg claim last-gasp winner, Gladbach close in on Wolfsburg|
|Pochettino: Hart heroics the difference|
|Ligue 1 Review: Monaco remain on course for third, Lille cruise past Lens|
|Pellegrini silent over City future|
|Rome derby not on Lazio´s radar, says Pioli|
|Pardew laments penalty calls in Palace´s loss to champions|
|Serie A Review: Roma move back into second, Di Natale overtakes Baggio|
|Tottenham 0 Manchester City 1: Aguero heaps more misery on Spurs|
|Mourinho appears to take dig at old nemesis Guardiola|
|Mancini frustrated by resilient Chievo|
|Drogba coy over future after title triumph|
|Chelsea title win will not lead to domination - Mourinho|
|Inter 0 Chievo 0: More frustration for Mancini|
|Terry: I´ve proved Benitez wrong|
|BREAKING NEWS: Chelsea secure Premier League title|
|Chelsea 1 Crystal Palace 0: Title heads back to Stamford Bridge|
|League One Review: MK Dons promoted, as Orient, Notts County and Crawley go down|
|Dortmund striker Ramos set to miss Copa America|
|Williamson denies getting sent off on purpose|
|Eintracht Frankfurt´s Kittel suffers injury blow|
|Juventus v Real Madrid: Serie A kings set for Real test|
|United still control top-four destiny - Young|
|Record finish beyond Stoke - Hughes|
|Wellington Phoenix 0 Melbourne City 2: Surprise win sets up semi-final derby|
|Vidal already focused on Real|
|MLS Review: Revs hand Red Bulls first loss|
|AFC Champions League Preview: Wanderers facing elimination|
|Lyon stepped up despite pressure - Fournier|
|Gerrard anticipating emotional Anfield finale|
|´I´ve always wanted to score a free-kick past Neuer´ - Calhanoglu|
|Negredo: Pellegrini lost faith in me|
|Buffon had title doubts after Conte departure|
|Luis Enrique: I was worried during 8-0 win|
|Wilshere will return to his best - Wenger|
|Rodgers unconcerned by banner|
|Mourinho doesn´t want guard of honour|
|Deportivo La Coruna 1 Villarreal 1: Hosts come from behind|
|Juve canter to title success as Allegri wins over doubters|