Barcelona should be favourites to qualify. Despite being second in their group, they are yet to play Royal Antwerp - who have lost all 4 matches so far - and will play their next match at home against Porto who they have already beaten in the away game in Portugal. Barcelona also boast a record of 8 wins in 9 at home this season - the 1 loss coming against a formidable Real Madrid side.
Having convincingly seen off Antwerp in the first game of the UCL season, Barca can be confident that the last match of the season will be a walk to 3 points. In the unlikely event that they do lose to Porto in their next match, they still have the game against Antwerp as a lifeline. Shakhtar, who are the other team in the group battling for qualification, also play Antwerp before travelling to Portugal to face Porto. They have already lost to Porto embarrassingly at home, and would not have high hopes for the return leg.
Barring a complete capitulation from Barcelona against either side they will face, their goal difference would be sufficient to get them through if they do lose to Porto at the Camp Nou, as unfathomable as that is. They essentially have their fate in their hands. Comfortable wins against both teams should be expected, especially seeing as they were able to see off Porto at their home ground in the reverse fixture, and that Antwerp has been so bad thus far.