The attacking midfielder feels Shakhtar should have done better in front of goal at Old Trafford and added that the Ukrainians now aim to win the Europa League
The Ukrainians created a number of good chances at Old Trafford, yet failed to find the net as David de Gea proved to be too great an obstacle.
The 1-0 loss proved costly as Bayer Leverkusen beat Real Sociedad by the same scoreline to leapfrog Shakhtar in the table, meaning Douglas Costa and his team-mates will be playing in the Europa League after the winter break.
"Our failure to take our chances [in the first half] had a real impact on the game, because we could have scored those goals. But we lost – that's football," the Brazilian told the official Uefa website.
"We didn't expect the night to end like this, but it's a lesson for us. We are learning, and now we have to turn the page and try again next season.
"Now the Europa League: I think we've played in it once and won it [in 2009]. We will try to do that again. For us, and any other team, the Europa League is also important."
Donetsk finished third in Group A with with eight points from six games, two points behind runners-up Leverkusen.