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'
|UEFA Europa League Preview: Brondby and Slovan to protect handsome leads|
|Bentaleb pens new long-term deal at Tottenham|
|Barca agree Turan deal|
|FIFA bans Mayne-Nicholls|
|United States v Honduras: Klinsmann demands improvement ahead of Gold Cup opener|
|CONCACAF institutes extensive reforms in wake of FIFA corruption scandal|
|Mauri completes Milan move|
|City sign Turkey striker|
|Women´s World Cup final draws huge US TV ratings|
|My first Chelsea team better than current crop - Drogba|
|Bertrand set for lay-off after knee surgery|
|New five-year Juve deal for Marchisio|
|Allegri extends Juve contract|
|Koeman reiterates Alderweireld interest|
|Valencia bag Bakkali|
|New York City FC complete Pirlo capture|
|Panama v Haiti: Collat ready to challenge the best of CONCACAF|
|UEFA Champions League Preview: Harrison eyes TNS progression|
|FIFA sanctions Yemen for fielding ineligible player|
|Toulouse rubbish Ben Yedder exit reports|
|Mourinho ´knows what he´s doing´ with Falcao signing|
|Watford shell out club-record fee for Capoue|
|Braafheid signs Lazio extension|
|Nani finalises Fenerbahce move|
|Liverpool confirm O´Driscoll appointment|
|Liverpool have to start better - Lucas|
|USA simply too good - Sasaki|
|Portland Timbers 1 San Jose Earthquakes 0: Jewsbury wins it in stoppage time|
|No move yet for Van Persie|
|Lloyd wins Golden Ball, Silver Boot awards|
|Mascherano: I never grabbed Banega|
|Dunga requested Brazil not appeal Neymar´s suspension|
|United States 5 Japan 2: Lloyd stars with hat-trick|
|Fiorentina deny Inter criticism|
|Nani relishing Fenerbahce opportunity|
|Newcastle hold talks over Northampton youngster|
|Cuadrado´s agent plays down Chelsea exit rumours|
|Liverpool´s Alberto set for Deportivo loan|
|Leverkusen suffer surprise defeat, Stuttgart hit six|
|Inter ´dismayed´ at Fiorentina vice-president´s Salah Twitter outburst|
|Blaszczykowski ruled out of Dortmund´s Asia tour|
|Gerrard gets the beers in for LA Galaxy fans|
|De Gea coy over Real links|
|Former Brazil star Carlos handed Delhi reins|
|Ciftci will not push through Celtic switch – agent|
|In-demand Mitrovic considering Roma offer|
|Lehmann calls on Cech to ´get over´ Chelsea|
|Marlos double sinks Monaco|
|Mauritius 0 South Africa 2 (agg 0-5): Bafana set up Angola qualifier|
|Keane relishing Gerrard arrival|
|Palace confirm Cabaye interest|
|Hamburg bring in Spahic after head-butt ban|
|Blatter hits out at France and Germany over World Cup votes|
|Sanchez: World Cup exit spurred Chile to Copa glory|
|Jojic makes Cologne switch, Santana move falls through|
|Carrillo keen to get going at Monaco|
|Micronesia thrashed 38-0 as Fiji triumph in Olympic qualifier|
|Schalke stunned by ´machine´ Caicara|
|MLS Review: Keane shines at Gerrard´s Galaxy unveiling|
|Counter-attacking the key for Japan|
|Jimenez happy at Atletico|
|Gerrard predicts ´successful future´ with Galaxy|
|Iniesta can´t see Real selling Ramos|
|Keshi sacked as Nigeria coach|
|Three finals, three defeats for Messi, Mascherano|
|Nani close to Fenerbahce move|
|Sampaoli revels in ´unbelievable joy´|
|Bravo: Copa victory a dream|
|Martino: Argentina should have won|
|Chile 0 Argentina 0 (4-1 on penalties): Hosts end trophy drought|
|Germany 0 England 1 (after extra time): England make World Cup history|