It means they will be drawn against a victor of another group in Monday's last-16 draw and, as UEFA regulations prohibit teams from the same nation facing each other in the first knockout round, Lionel Messi's Barca and Neymar's PSG are among the few possible opponents.
Manchester United came back to win 2-1 against CSKA Moscow to book their passage to the round of 16 as finished first place in Group A. However, just because they finished in first doesn't mean that they'll get any cupcakes. Real Madrid are also confirmed to finish second and will be joined by three more sides - now scheduled to be Sevilla, Shakhtar Donetsk and Porto. That means Chelsea can not draw Roma, Manchester United can not be drawn to play against Basel and Tottenham will not be up against their Group H opponents Real Madrid.
Cahill won the European Cup in 2012 with Chelsea, who remain the most recent English team to make the final.
The last side to beat United at Old Trafford was Manchester City, who visit the stadium in Sunday's crucial title clash.
The Blues had entered the final round of group matches in pole position, but the result at Stamford Bridge and Roma's 1-0 home win over Qarabag saw the Serie A side win the group by virtue of their superior head-to-head record against Chelsea.
Barcelona: Bayern Munich, Chelsea, FC Basel, FC Porto, Shakhtar Donetsk.
"In this case, we know we could play Barcelona, PSG or Besiktas".
Manchester United and Juventus qualified for the Champions League knockout stage on Tuesday, while three-time runners-up Atletico Madrid bowed out of the competition.
Sevilla: Besiktas, Manchester City, Manchester United, Paris Saint-Germain, Roma, Tottenham Hotspur.
The draw for the Last 16 will commence in Nyon on Monday afternoon. The first legs will be played on 13, 14, 20 and 21 February, and the second legs will be played on 6, 7, 13 and 14 March 2018.