Manchester United midfielder Michael Carrick says they must not take Champions League opponents Braga lightly.

The Geordie admits the Portuguese are an unknown quantity.

Carrick said: "It can be quite tough in the Champions League to judge [who will qualify from each group]. Some people might pick out two teams in a group and say they will be the top two and the others will struggle. Quite a lot of the time, that is not the case.

"It isn't necessarily the teams that catch your eye [namewise] who are the ones that cause you problems. We know even in Cluj, it wasn't straightforward. The lads had to play well to get a result. That is the nature of European football.

"Braga are a good team. You have to respect them for getting to this stage to start with. It is not easy in any league to go through the whole season near the top [and qualify for the Champions League]. You have to respect them. They are going to be of a certain standard and we have to match it."