While there is always interest and entertainment on show in the group stage, for most fans the Champions League begins properly when it reaches the knockout phase - and that's when bitcoin betting takes up new heights. The wheat has mostly been separated from the chaff, as the majority of the continent’s top 16 sides in the UEFA rankings have made it through to this point.
Of those that didn’t, two didn’t qualify for the competition anyway (Sevilla and Arsenal), Napoli were the odd one out of the three top 16 teams who were in Group C, and Shakhtar Donetsk were 25 minutes from making it through until they conceded an equaliser to Lyon.
Similarly, none of the other teams still in the competition are ranked below 25th in Europe. There are clearly no real outsiders left in the draw, even if only a handful of sides currently harbour realistic hopes of going all the way and lifting the trophy in Madrid in June.
The draw for the last sixteen always follows the same pattern. Group winners are drawn to face runners up, with the latter sides playing the first leg at home. In seven of the eight ties, the group winner is the higher ranked of the two teams. Even in the one exception – Atletico Madrid vs Juventus – they are side by side in the rankings, it isn’t a massive mismatch. Seeding works.
A historical look at seeding
But has it worked over the years? The current system has been in place since the 2003/04 season. For the four seasons prior to that, UEFA had implemented a second group stage round. Our study will therefore focus on the last 15 seasons where it has been straight knock-out from the last 16 onwards.
Of the 120 ties at this stage in this period, the side playing away first has gone through on 85 occasions, or 71% of the time. That percentage drops to 62% in the quarter-finals, and 37% in the semi-finals, but in those rounds there are no seedings. This is the only knockout round in the Champions League which has them, and it appears to make a difference.
Even then, it’s not always the weaker team which plays at home first at this stage. Big teams have been known to have slow starts in the competition and qualify as runners up in their group. Seven of the 35 times a team has played at home first and qualified were by Bayern Munich and Real Madrid, for instance.
Not every group winner is the favourite to qualify in 2019 either. The margins are narrow, but bookmakers think Roma and Liverpool will progress at the expense of Porto and Bayern respectively. If any group winners are to be eliminated this year, what does history suggest the runners up will need to do to come out on top?
What the data says
It won’t surprise you to hear that winning the first leg obviously helps. Twenty-five of the 35 sides who played at home first and reached the quarter-finals won in front of their own fans. Not that it offers any guarantee though – there are 20 teams who’ve won the first leg at home but still gone on to be eliminated from the competition in the return match.
Nine group stage runners up have advanced after drawing the first leg at home – with six of them conceding away goals in score draws, perhaps surprisingly – leaving just one team who lost at home but still made it through.
Bayern Munich were in dreamland when Mario Gomez’ last minute goal gave them a 1-0 victory against Internzionale at the San Siro in 2011. However, goals from Eto’o, Sneijder and Pandev helped the Italian side to a 3-2 win in the return leg, and a place in both the quarter-finals and the record books.
Not only are the only team to lose at home in the first leg of a last sixteen tie and advance in the last 15 seasons, but they’re the only one to do so in any Champions League knockout tie in any round in that period.
There’s been 210 ties in the last decade and a half, and Inter stand alone for this feat. Having beaten Bayern in the previous season’s final, the German side must’ve been sick of the sight of them. If it took a reigning European champion to overturn a first leg home defeat, it’s unlikely any of 2018/19’s last 16 first leg hosts will be able to do likewise if they are behind at the half way point of the tie.
Is there hope for underdogs?
While keeping a clean sheet at home in the first leg obviously also helps, it’s not as decisive as you might think. Sixteen of the 35 clubs who made it through to the last eight after playing on home turf first kept their opponents to nil in the opening match of the tie, but there are another 16 who kept a clean sheet but eventually went out.
What appears to matter more is scoring the first goal of the tie. There have only been nine instances in the past 15 seasons where a team has conceded the first goal at home in the first leg and got through. The other 26 first leg home teams who made it through scored first, with three – Roma in 2007, Arsenal in 2008 and Sevilla last year – having to wait until the second leg to break the deadlock after a 0-0 draw.
The frequency of group runners up who make it to the last eight appears to be on a slight decline. There were 10 in the last five seasons, 12 in the five years prior to that, and 13 in the half decade before that. History suggests if any side is going to get through in 2019, they need to score first and almost certainly avoid defeat in the first leg.