Already assured of a spot in the knockout phase after Group H leaders Porto won 3-0 at BATE earlier on Tuesday, Shakhtar were beaten 1-0 by visiting Athletic on matchday five, who were winless previously.
Mikel San Jose scored the only goal of the match in the 68th minute, benefiting from some slack Shakhtar defending at the Arena Lviv.
Shevchuck insisted the Ukrainian powerhouse did not get complacent following Porto's result in Belarus with top spot on the line, claiming Shakhtar - five points adrift in second spot - just lacked creativity in the final third.
"Of course, everyone knew that we are competing for the top spot. Journalists talked before the match that Athletic did not need anything ," the 35-year-old left-back was quoted as saying on Shakhtar's official website.
"But we were seriously preparing for the game, trying to attack throughout the encounter, it just didn't work offensively today."
Shevchuk added: "We always have it [motivation]. Shakhtar are a very motivated team. All players want to play and win, produce a top-level performance.
"This is Europe, UEFA Champions League here, lack of motivation is impossible - everyone comes out with the right attitude."
