Alex Sandro admits Juventus failed to live up to standards for defeat at Champions League opponents Porto.
Juve return to Turin for the second-leg of their round 16 tie needing to overturn a 2-1 deficit.
“We knew that the first half was bad, but the second was better and we are well aware that we must start the second leg the way we ended this match," Alex Sandro told Sky Italia.
“There were big mistakes on two incidents and they took advantage to score two goals, so we need to be more concentrated in these situations."
The result comes just days after their 1-0 Serie A defeat at Napoli.
“We talked about this after the Napoli game, as that was more or less the same thing," confessed Alex Sandro.
“Again we started that match badly and ended it much better, so what we need to do now is learn to start strong.
“Having said that, we did score a goal this evening and hopefully it can set us up to do better in the second leg."
