The knockout play-off is the Swiss-format era's bridge round, contested across two midweeks in February by the sixteen clubs that finished ninth through twenty-fourth in the league phase. League-phase seeding determines pairings: ninth play twenty-fourth, tenth play twenty-third, and so on, with the higher-ranked club playing the second leg at home. The eight winners advance to the round of sixteen, where they meet the eight clubs that finished directly in the top eight. The eight losers drop out of European competition for the season — there's no parachute to the Europa League under the new format. The round has produced significant upsets: lower-pot clubs that took a points haul through the league phase have repeatedly toppled elite seeds in the play-off.
Format — how the play-off works
Sixteen clubs ranked 9th-24th in the league phase enter the knockout play-off. Pairings are pre-determined by league-phase finishing position: 9 vs 24, 10 vs 23, 11 vs 22, 12 vs 21, 13 vs 20, 14 vs 19, 15 vs 18, 16 vs 17. The higher-ranked club hosts the second leg. Ties are decided over 180 minutes of aggregate score, then 30 minutes of extra time, then penalty kicks. Away goals do not count double under UEFA's post-2021 rule change.
Bracket implications
Round-of-16 opponents are also pre-determined: the 9 vs 24 winner faces the league-phase 8th-placed club, with progressively higher seeds for play-off winners that emerged from harder pairings. This means clubs entering the play-off already know — if they win — exactly which top-eight side they'll meet in the round of sixteen, and that the round-of-16 second leg will be played at the top-eight club's stadium.
Form patterns
Across the play-off rounds since the format launched, lower-seeded clubs that finished 17th-24th have a stronger upset record than the seeding suggests — typically two or three of the eight ties produce a 'wrong-side' winner. Travelling fans should budget for the second leg even if the lower seed loses the first leg at home; the format produces tighter aggregate scores than the old straight-draw round of 16.