“What’s the furthest a team has gone in Europe while being relegated in the same season?” wonders Matt Reilly.

This question was probably asked in reference to Tottenham, who were still in the Champions League at the time, but it’s still relevant to some of this year’s quarter-finalists. Nottingham Forest are three points above the relegation places in the Premier League; Fiorentina only have a five-point cushion in Serie A.

Celta Vigo, who sit sixth in La Liga and will play Freiburg in the Europa League quarter-final, are surely safe. But that hasn’t always been the case. “Celta Vigo went from fourth in La Liga in 2002-03 to 19th the next year, crashing straight back down to earth,” writes Ciaran Hannigan. “But in the Champions League they beat Slavia Prague, came second in a group with Milan, Club Brugge and Ajax, before being put away by Arsenal in the round of 16.”

Perugia reached the last 16 of the Uefa Cup in the same season before going out to PSV Eindhoven. European success was not replicated in Serie A: they failed to win any of their first 22 games and were eventually relegated via a playoff. Two years later,...