That outing is the World Cup-winning goalkeeper’s 175th appearance in European competition, edging him ahead of legendary Milan defender Paolo Maldini on that particular roll of honour.
The vast majority of those outings came during Casillas’ time on the books of Real Madrid, with 16 years spent in the first-team fold at Santiago Bernabeu.
He has also taken in regular continental outings since linking up with Porto in 2015 and now holds an impressive record outright.
During his days in Madrid, Casillas tasted three Champions League triumphs - with their La Decima success of 2014 proving to be his last.
He also secured two UEFA Super Cup titles as part of an enviable collection of silverware secured in the Spanish capital.
There is work to be done in his latest European outing, though, with Porto heading into the second leg of their last-16 showdown with Juve trailing 2-0 on aggregate.