The interview could put more pressure on under-fire Manchester United manager Dutchman Luis van Gaal, whose charges have been widely accused of being boring this season.
In July 2014 Adidas signed a ten-year kit sponsorship deal with the English Premier League club worth £750 million (1 billion euros, $1.1 billion).
Van Gaal acknowledges Man Utd pressure
"The business side of things is going very well," Hainer told the newspaper in reference to massive shirt sales.
"But the current style of play is not exactly what we wanted to see," he added.
The sportswear company also has kit deals with Real Madrid and Bayern Munich.
Winners of the Champions League in 2008 and 1999 and its predecessor the European Cup in 1968, United invested heavily in the last close season bringing Anthony Martial, Memphis Depay and Bastian Schweinsteiger into their squad.
But United currently sit outside the Premier League top four, have been knocked out of the Champions League and were even eliminated from the English League Cup.
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