Rugby correspondent Niall Crozier tackles all the battles in tonight's game
Johann Muller v Marco Bortolami
Both sides will be led tonight by totemic figures in their respective engine rooms with Ulster's South African skipper Johann Muller facing off against the 99-times-capped Italian international Marco Bortolami.
Muller, who won the World Cup with South Africa back in 2007, is feeling his way back into action after missing a month with a torn calf muscle while Bortolami recently returned to the Zebre side for the pair of Heineken Cup losses to Saracens having spent November with the national side for their autumn internationals series.
Born just 11 days apart, both men are 33-years-old, but remain hugely influential figures for their respective sides and provide experience and leadership that will be important tonight given that both coaches have named decidedly makeshift line-ups.
Bortolami is something of a talisman for the Italian side having spent four years as a central figure for Gloucester in the English Premiership. The predecessor to Sergio Parrise as national captain, he is three inches shorter than Muller at 6'4'' but both tip the scales at 246lbs.
Niall Annett v Andrea Manici
With the new contract signed by Rory Best this week, as well as the impressive performances of Rob Herring recently, Niall Annett could be a man short of appearances in the coming months but he gets a chance to impress against Zebre tonight.
The former Methodist College player will be opposed by Andrea Manici.
The 23-year-old Manici has one Italian cap, coming against Samoa in the Quadrangular Tournament last summer, having previously appeared for both the u-20 and A sides.
With the likes of John Afoa, Rory Best and Declan Fitzpatrick missing for Ulster, and Zebre without over 100-caps worth of international experience due to the absence from the start of props Salvatore Perugini and Matias Aguero, how the relatively new front-rows perform could have a huge bearing.
The young hookers will be central to that while the forecast poor weather will likely have them pausing for thought during set-pieces.
Paddy Wallace v Roberto Quartaroli
It has been nine long months since Paddy Wallace injured his ACL, but the inside-centre returns tonight to make his 189th competitive appearance for Ulster.
The 30-times-capped Irish international made two starts for the Ravens over the last fortnight while his team-mates were in Heineken Cup action but is now ready to return.
How his knee responds to the rigours of PRO12 rugby will be tested by Roberto Quartaroli, Zebre's 25-year-old Italian who won the last of his five international caps against the USA in the summer of 2012.
As well as being nine years Wallace's junior, Quartaroli enjoys a considerable size advantage over his opponent, standing at 6'3 and 209lb compared to Wallace's 5'11 and 178lb, but the Ulsterman is a canny operator and will look to use all his experience to get the better of the duel.
The main threats
Complacency has been the buzzword in Ulster camp this week – both head coach Mark Anscombe and his assistant Neil Doak have already spoken out about it – and it's something the players must avoid as they look to maintain the momentum gained from taking maximum points in the Heineken Cup double-header with Treviso.
Much is often said about the drop in intensity when returning to the more prosaic matter of the PRO12 following European action, but Mark Anscombe's side will need to come out firing to avoid giving the visitors even the slightest hint that this could be their night.
The men from Parma may have been on the receiving end of consecutive thrashings at the hands of Saracens over the last fortnight, but have shown signs of improvement this year, winning away at Cardiff, drawing at home to Scarlets and running Edinburgh close in Murrayfield, so the potential for an upset is there if Ulster don't focus.
With spots to be earned for the festive inter-pros, however, a much-changed line-up should not be lacking in motivation.
Ulster have had no problems crossing the whitewash in recent weeks, securing a bonus point in three of their four contests since the international break.
The try glut has featured some sparkling play from their much vaunted backline, with the offloading ability of the likes of Jared Payne and Darren Cave drawing praise from all corners.
Cave is given a well-earned rest tonight – Payne is joined in the midfield by the fit-again Paddy Wallace – but Ulster will still look to move the ball around with a pace and flair that their Italian opponents are unlikely to match.
If the new centre partnership clicks for Mark Anscombe's men then it could be a highly productive night for Ulster's wingers.
Zebre will hope to nullify that threat by holding on to the ball and moving through the phases.
With plenty of physicality in their pack, Andrea Cavinato will send out his forwards with the instruction that disrupting the rhythm of Payne, Wallace and Ruan Pienaar is absolutely imperative to their chances of success.