Whose names are not always easy to recall: Saints Nazarius and Celsus, Pope Victor I (all three of them martyrs) and then of Pope Innocent I, Confessor. As is obvious from the snippet of the Martyrology I stick to the bottom of the page, I had forgotten that the celebrations of Popes Victor and Innocent had been at some point combined with that of Saints Nazarius and Celsus. The Mass is Intret in conspéctu tuo, Dómine (Introibo; CE, Saint Victor here and Saint Innocent here; Wiki, Saint Victor here and Saint Innocent here).
Victoria's motet Gaudent in caelis is for feasts of several martyrs-- I lack the patience this morning to search further in YouTube for recordings of the parts of the Mass Intret.
It is also the feast of Pope Saint Victor (2nd century), of Saint Geranius (10th century), and of Saint Samson (6th century).
V. Et álibi aliórum plurimórum sanctórum Mártyrum et Confessórum, atque sanctárum Vírginum. R. Deo grátias.