Radja Nainggolan rejected the suggestion that complacency was the reason for Roma's shock 3-2 loss to BATE in the Champions League.
The Serie A side paid the price for a woeful first-half display in Belarus that saw them concede three goals.
“We knew it would be a tough game, so there was no complacency, but if we had played the first half the way we did the second, it would’ve been different," he told Mediaset.
“It’s our fault, we are aware that it was a game of two halves that we should’ve played for 90 minutes.
"We just have to take this as a lesson and try to learn for the next time.
"If we had a different start, it would’ve been a very different game. We knew what we had to do, it’s just that we didn’t do it very well. Now we have to see what went wrong. Clearly we should have done better."
Roma's next outing in Europe sees them visit Bayer Leverkusen, the first of back-to-back matches against the German side.
