Dzeko insists Roma are now returning to their best form.
"We're feeling confident after three wins in a row, the team is in good shape and we are really enjoying the new system," the striker told AS Roma Match Program.
“Shakhtar have great technique in their squad and played only one competitive game after their winter break, so physically we might have the advantage. We've got to give our all and make the most of the situation."
The Ukrainians have a large Brazilian contingent and finished ahead of Napoli in their Champions League group.
“Along with Liverpool, Shakhtar are the only side to have beaten Manchester City this season and Pep Guardiola's men are the best around right now. These ties are decided over 180 minutes, not 90, and we must think of the big picture.
“I don't know if playing the first leg away from home is an advantage or not, as recently we've been struggling for goals at home. We have players with experience in Europe, not just me, Daniele De Rossi and Aleksandar Kolarov. We know what we have to do."