Barça, Borussia Dortmund, Inter Milan and Bayern Munich have all qualified for the Champions, with the three teams in Europe’s elite competition winning the last two titles.
The winner of the Champions league will be the European champion and it is expected that the winners will go straight into the final as the league is the highest tier in Europe.
Barcelona will be looking to secure their first Champions League title since 1997 after beating Manchester United and Juventus in their opening round.
However, they have only won the Champions twice before and were knocked out by the reigning champions Real Madrid in the quarter-finals.
Inter Milan and Juventus were knocked down by Barça in the first round of the Europa League.
They are also the only teams not to have won the European Cup since 2007.
With the last four Champions League winners Bayern Munich and Borussia Mönchengladbach not going through to the final, Inter are in a stronger position to make a run into the last 16 than the other teams.
There are still four more games to play and they are still favourites to make the final.
Barça were also eliminated from the Champions after beating Real Madrid and Real Sociedad in their first round.
Borussia Dortmund and Inter Milan are currently third in the Bundesliga, with Inter currently leading the standings with 12 points.
Borussiad are currently sixth in the standings.
Dortmund were knocked off by Manchester United in their opener, but have bounced back with wins over Tottenham Hotspur and Barcelona in their next two games.
Milan are in seventh, while Bayern are eighth.
Real Madrid and Inter will play their first leg at the Bernabeu in the second leg on Sunday, while Dortmund face Inter in the last game of the group stage on Wednesday.
In the final match, Inter will host Barça.