The 46-year-old Irish musician's two-day run at Vicar Street may be completely different from one night to the next, but the Monday night leg of the gig sees a host of unannounced guests. Can you guess who?

Slyly mentioning the Czech woman Markéta Irglová early on in the show, as if she wasn't in the room or country, Glen shocks the crowd by welcoming his long-time friend to the piano.
As expected, the two play 'Falling Slowly' and a slew of songs they co-wrote. Marketa sticks around for the rest of the evening, making a final appearance for the group sing-along of Mic Christopher's 'Hey Day.'

Recalling an email he received about a guy who could "apparently sing Glen Hansard songs 'good'. Damien Rice 'good'. Mic Christopher 'good'," etc.., he beckons the man himself, John Byrne, to join him on stage for a song.

After much encouragement, he makes his way up front, only to be left alone with Glen's guitar. He starts to play 'Falling Slowly' but is cut short by Glen saying "Not that one!" The young man chooses 'Leave' only to forget the words for the second verse! Mr. Hansard provides no support as he seems to have forgotten as well. Thank goodness for the crowd, who tries to fill in as well.

Part way through the gig, Glen asks "Is Danny Sheehy anseo?"
Someone yells "Tá!" from the balcony. Coaxing his seafaring friend Danny to come to the stage with a whiskey, Glen explains how over the summer he joined the poet for a currach excursion from Ireland to Northern Spain.
Once on deck, the man holds up his glass (full of whiskey, perhaps), and recites this poem:

Danny Sheehy's poem to the Whiskey.. In Irish first, then English below.. pic.twitter.com/v2K4Y6kQ0y

— Glen Hansard (@Glen_Hansard) June 14, 2016

One highlight of the memorable show comes as part of the encore when Glen introduces the magnificent Spanish guitarist Javier Mas. Sitting down with the band the whole night, the man who played with Leonard Cohen's band for many years, enchants the audience with his magical bandurria solo that leads into 'Who By Fire.' They go on to cover 'The Partisan' and 'Famous Blue Raincoat,' capping it off with Glen's personal tribute to Len, 'Her Mercy.'

Among fan favourites like 'Star Star' and 'When Your Mind's Made Up,' the set warmly embraces a Van Morrison cover 'Astral Weeks' and an ever-relevant Woody Guthrie piece titled 'Vigilante Man.'

If the sold-out Monday show is any indicator of how tonight's event will play out, then fans have much to look forward to and should ready themselves for many treats.