Manchester City and Celtic are among the teams with work to do if they are to advance into the last 16 of the Champions League.

With the knockout phase play-offs getting under way on Tuesday, City fell to a 3-2 home defeat to European champions Real Madrid, while Celtic lost their first leg 2-1 to Bayern Munich on Wednesday.

Meanwhile, both Paris St-Germain and Borussia Dortmund won 3-0 away from home to Brest and Sporting respectively, and appear strong favourites to advance.

But what is the state of play in the other play-off ties? And who is already through?

Manchester City had come from behind to beat Club Brugge to squeeze into the play-offs and they will now need to overturn a first-leg deficit in the Bernabeu if they are to advance any further.

Celtic, who like City, are among six sides to trail by a single goal heading into next week, will also face a huge challenge to overcome six-time European champions Bayern, if they are to progress.

Of the other British clubs, Aston Villa, Arsenal and Liverpool have already booked their place into the last 16, having automatically qualified in the top eight of the league phase.

These are the teams in each stage:

Last 16: Liverpool, Barcelona, Arsenal, Inter Milan, Atletico Madrid, Bayer Leverkusen, Lille, Aston Villa.

Knockout phase play-offs: Atalanta, Borussia Dortmund, Real Madrid, Bayern Munich, AC Milan, PSV, Paris St-Germain, Benfica, Monaco, Brest, Feyenoord, Juventus, Celtic, Manchester City, Sporting, Club Brugge.

The full draw for the play-off round is as follows:

Brest 0-3 Paris St-Germain (second leg 19 February)

Juventus 2-1 PSV Eindhoven (second leg 19 February)

Manchester City 2-3 Real Madrid (second leg 19 February)

Sporting 0-3 Borussia Dortmund (second leg 19 February)

Club Brugge 2-1 Atalanta (second leg 18 February)

Celtic 1-2 Bayern Munich (second leg 18 February)

Feyenoord 1-0 AC Milan (second leg 18 February)

Monaco 0-1 Benfica (second leg 18 February)

Liverpool and Barcelona cannot meet until the final now after finishing in the top two of the league phase.

The Reds will play one of Monaco, Brest, PSG or Benfica in the last 16 - with Barca facing another of those teams.

Arsenal, who finished third, will play Feyenoord, Juventus, AC Milan or PSV.

Aston Villa, who just finished in the top eight after beating Celtic in their final group game, will take on Sporting, Club Brugge, Atalanta or Borussia Dortmund.

Those ties will take place on 4-5 and 11-12 March.

But they will not know which team exactly until the last-16 draw takes place on 21 February.

Clubs will know their potential route to the final by then - with the draws for the quarters and semis also taking place that day.

There is a chance Liverpool and Aston Villa could meet in the quarter-finals if they both win their last-16 ties.

Arsenal could meet Celtic or Manchester City in that round too.

But all of those potential fixtures depend on which way the last-16 draw goes. It is also possible British teams could meet in the semis or final.

All should become clearer after 21 February when the draws for the last 16 onwards are made.