The phrase "unprecedented treble" means achieving or accomplishing something that has never been done before in three different aspects. Full definition
Get well soon, our bandage warrior, so you can lead us past a resurgent Real Madrid and a relentless Napoli in our quest for an unprecedented treble. (sbnation.com)
Fergie's Reds take on Newcastle at Wembley aiming to complete part 2 of an unprecedented treble. (mutv.manutd.com)
Later in the same decade, the famous 1998/1999 side that won an unprecedented treble developed a habit of popping up with late goals — with a never - say - die attitude thoroughly ingrained in them. (eplindex.com)