Who is on track to qualify in the Champions League?

Liverpool lead the way and are well on track to progress in the Champions League - but could Manchester City and Arsenal be in danger of missing out on a top-eight spot?

We're half way through the revamped Champions League's new 36-team league phase and the table is beginning to take shape.

Each club has now played four of the eight different teams they must face to decide who will qualify for this season's knockout stages, following the most significant update to Europe's elite competition since 1992.

There has been no shortage of heavyweight clashes, significant shocks and high-quality entertainment.

But where does it all leave us and what has it meant for each clubs' hopes of qualifying?

Who qualifies for the knockout phase?

Before we dive in to which teams appear on their way to the knockout stages and who is in potential trouble, here's a reminder of what they are aiming for.

Teams finishing in the top eight automatically progress to the last-16, where they will be seeded.

They will await the winners of eight two-legged knockout play-off ties featuring the clubs ranked from ninth to 24th.

Those finishing between ninth and 16th will be seeded and face a team placed 17th to 24th, with the advantage of playing the second leg at home.

The clubs 25th or lower are eliminated and do not gain entry in to the Europa League.

How many points are needed to qualify?

Given this is the first edition of the new format, it remains to be seen exactly how many points will be required to achieve a valuable top-eight finish, or avoid elimination from the competition.

Before this season's competition, Opta calculated each teams' projected points tallies and likelihood of progressing based on 50,000 simulations of the league phase.

They found that 16 points - potentially five wins and one draw from eight matches - would give a 98% chance of finishing in the top eight.

Meanwhile, achieving 10 points - three wins and one draw, for example - would give a 99% chance of securing a place in the top 24.

However, any team collecting fewer than nine points can expect their involvement in European competition this season to come to an end.

Which clubs are on track and who has work to do?

Manchester City have won two of their four games in this season's Champions League

Leaders Liverpool, who face champions Real Madrid next, are the only team to boast a perfect record after four games.

They would require just four more points from their remaining four games to be assured of a place in the last 16 and have a 98.8% likelihood of achieving that, according to Opta's projections.

Sporting - following their stunning 4-1 win over Manchester City - Monaco, Brest and Inter Milan are all in great shape, having already achieved the 10 points likely needed to confirm qualification of some form.

Aston Villa - despite their perfect start being ended by Club Brugge - complete the current top eight behind Barcelona and Borussia Dortmund, each on nine points.

Villa opened with three wins - and stunned Bayern Munich - to boost their hopes of reaching the last 16 to 65%, although with Juventus, RB Leipzig, Monaco and Celtic to come there is a 64.7% likelihood they will have to go via the play-off.

There are plenty of European heavyweights still outside those top eight positions, with Manchester City, in 10th, and Arsenal, 12th after losing to Inter Milan, on seven points and therefore not on pace to hit the 16-point target.

However, Pep Guardiola’s side remain favourites to win the competition for a second time, still with a 91.1% chance of reaching the last 16 and a 19.3% chance of claiming the trophy.

Arsenal are given an 80.0% chance of progressing to the last 16 but also a 58.4% chance of having to go through the knockout round play-off to do so.

City have Juventus and Paris St-Germain among their remaining fixtures, while Arsenal must face high-flying Sporting and Monaco in their next two.

Celtic are 15th and also on seven points, having boosted their hopes with a second win, beating Leipzig 3-1 on Tuesday. They visit Villa in the final match on Wednesday, 29 January, when all 36 teams will play at the same time.

Celtic’s latest victory means Brendan Rodgers’ side - on the same points as the likes of Juventus (11th), Bayern Munich (17th) and Real Madrid (18th) - have a strong chance of making the top 24 (78.2%), with their last 16 hopes rated at 40.2%.

French champions Paris St-Germain are the biggest name outside the top 24, having won just one of their first four games and with City and Bayern Munich to come. The 2020 finalists are now given only a 43.4% chance of making the last 16.

View the Champions League table in full here.

Watch highlights of every Champions League game from 22:00 on Wednesday on BBC iPlayer and the BBC Sport website and app.

There will also be a Champions League Match of the Day on BBC One on Wednesday, from 22:40 to 00:00.