Barcelona last week managed something unprecedented but what does history say about the remaining ties. We look at each team's chances of going through from their current position.
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Last week Barcelona became the first side to advance through a major European tie having lost the first leg 4-0 – at the 59th time of asking!
So who does history say will go through in this week's round of 16 second legs, and is anyone else in line to pull off a 'Barcelona'?
We studied every past first leg in the European Cup/UEFA Champions League, UEFA Cup/UEFA Europa League and European/UEFA Cup Winners' Cup with an identical scoreline to the round of 16 ties and noted which teams progressed.
Oh, and if all six 'unseeded' sides hold on and go through, that too will make history ...
Juventus v Porto (2-0)
Home side in second leg through: 330 (97.3%)
Away side in second leg through: 9 (2.7%)
Leicester City v Sevilla (1-2)
Home side in second leg through: 287 (48.9%)
Away side in second leg through: 300 (51.1%)
Atlético Madrid v Bayer Leverkusen (4-2)
Home side in second leg through: 28 (96.6%)
Away side in second leg through: 1 (3.4%)
• The only team to fail to successfully defend a 4-2 lead at home were Barcelona, after a 4-1 loss to Metz in the 1984/85 European Cup Winners' Cup first round.
Monaco 3-5 Manchester City
Home side in second leg through: 4 (40%)
Away side in second leg through: 6 (60%)
Bonus UEFA Champions League round of 16 stat ...
How many seeds (home in second leg) have gone through
7: 2005/06, 2010/11
6: 2006/07, 2011/12, 2012/13, 2014/15, 2015/16
5: 2003/04, 2004/05, 2008/09
2: 2016/17 (4 ties complete)