ESPN's rugby predictions: Games of the week, potential upsets & more

European club rugby returns after a five-month absence, and the first round of fixtures should not disappoint. Last year's beaten Challenge Cup finalists Gloucester kick off proceedings against Pau on Thursday before the Champions Cup begins at the Kingspan with Ulster entertaining Wasps on Friday.

Here, ESPN's experts predict which teams are set for a big weekend, which players will shine and where your attention should be trained across the two competitions.

Player to watch

Champions Cup (Nick Bewley): Charles Piutau (Ulster). The former All Black has already stamped his mark on the European scene since leaving New Zealand and expect no different Friday when he lines up against former club Wasps. Piutau, 25, led the competition for the last two seasons in line breaks, and with the possibility of no European club rugby with Bristol next year, he will want to make every post a winner this term.

Challenge Cup (James Harrington): Jake Polledri (Gloucester). For Gloucester's trip to Pau, head coach Johan Ackermann has handed a full debut to England Counties flanker Polledri, as one of nine changes to the side that started against Northampton last time out. It's another milestone in an unusual career route for Polledri, 21, that has included a brief stint in Italy and an under-20 call-up for the Azzurri, before he returned to the UK at Dings Crusaders, Hartpury and, finally, Kingsholm.

Game of the weekend

Champions Cup: Exeter vs. Glasgow, Saturday, 7.45 p.m.

There's an argument that every fixture in Pool 3 could be a potential game of the weekend, such is the strength of the four sides that feature. First up for Premiership champions Exeter -- who have made a slow start to the season -- is the form team of the PRO14 in Glasgow, yet to drop a game. Both coaches have been suggested as future international bosses in Rob Baxter (England) and Dave Rennie (All Blacks), so expect a tactical ding-dong battle for the purists under the lights at Sandy Park.

Challenge Cup: Sale vs. Toulouse, Friday, 8 p.m.

The Challenge Cup's other Pool 2 match this week is impossible to ignore as two sides bursting with young talent clash at the AJ Bell Stadium. Steve Diamond's young guns have not always gelled so far, and will look to this competition as a chance to kickstart their season. But Toulouse are a very different beast to the lumpen, leaden outfit that limped to 12th place in the Top 14 last season and missed out on a place in the Champions Cup for the first time in their history.

Potential upset

Champions Cup: Northampton Saints vs. Saracens, Sunday, 5.30 p.m.

If there was ever a time to silence Saracens, it's Sunday for the Saints. Mark McCall's side sit top of the Premiership standings but are yet to be properly challenged with their big stars slowly reintegrating into the fold -- or in the injury ward. Northampton look formidable in the Premiership after a disastrous start -- ironically against Saracens -- on opening weekend, and if the likes of Courtney Lawes and George North can continue their strong early season form there could be a shock at Franklin's Gardens.

Challenge Cup: Cardiff Blues vs. Lyon, Friday, 7 p.m.

It's hard to say whether a victory for the Top 14 leaders over the fifth-placed PRO14 Conference A side should really be classed an upset. But Blues' thrilling comeback against Dragons in last Friday's Welsh derby will have boosted confidence levels ahead of their European opener at the Arms Park. The visitors, however, are looking for their third away victory in as many weeks before they entertain Sale on their return home after a month on the road.

Big weekend for...

Champions Cup: Ospreys. Their poor form this campaign has been slightly overlooked since Scott Baldwin was bitten by a lion a fortnight ago, but the numbers speak for themselves -- just one win from six matches. European bridesmaids Clermont arrive in Swansea determined to go one better than last year, but it hasn't exactly been smooth sailing in the south of France. They sit ninth in the Top 14 after seven rounds, with their last away win coming against Lyon back in April. A win for Ospreys could boot them out of their current rut.

Challenge Cup: Bernard Jackman. The Dragons' injury list is as long as the signpost at Llanfairpwllgwyngyllgogerychwyrndrobwll-llantysiliogogogoch railway station. Before last Friday's PRO14 derby against Blues, head coach Jackman reported 29 players were queuing for treatment outside the physio's room. The Welsh side kick off their Challenge Cup campaign at Newcastle's Kingston Park on Saturday, with the boss hoping his players will come home unscathed.