This week we turn our attention in our ones to watch series to the men in the No.9 jersey, with a variety of world-class talent among the five scrum-halves we have picked out in this season's Challenge Cup. Pool 1: Rory Kockott (Castres Olympique) The 33-year-old French international was an ever-present as Castres finished third in Pool 2 of the Heineken Champions Cup last season and will be an important figure as the TOP 14 club bid for their first European honours. The South African-born scrum-half has yet to play in the Challenge Cup, but he has been a major contributor to Castres’ European Cup campaigns with 126 points in 33 games. Pool 2: Nick Phipps (London Irish) Phipps’ signing is a major boost for London Irish on their return to the Challenge Cup. The 30-year-old won 71 caps for Australia before his move to England, including eight in the World Cup. A member of the Australia Sevens squad who won a silver medal at the 2010 Commonwealth Games, Phipps was a mainstay for the Super Rugby side Waratahs between 2014 and 2019. Pool 3: Dan Robson (Wasps) A Challenge Cup winner with Gloucester Rugby in 2015, Robson’s career has taken off since his move later that year to Wasps, where he was their regular No.9 in the Champions Cup until struck by injury last season. His eye for a break and searing pace have earned the 27-year-old a call-up to the England Saxons and then the senior England squad. He made his Test debut in February 2019 against France. Pool 4: Andy Uren (Bristol Bears) Uren enjoyed a superb campaign last season, scoring six tries in six games as Bristol reached the Challenge Cup quarter-finals for the first time since 2007. That tally lifted the 23-year-old into joint fourth place in the 2018/19 Challenge Cup try-scorers' list and he also featured in the competition’s top eight for breaks (12) and metres made (430). [jwplayer Fao1Lmpk] Pool 5: Ben Youngs (Leicester Tigers) England’s most-capped scrum-half with 88 Tests is now Eddie Jones’ first-choice No.9 and looks set to be a mainstay in Leicester Tigers’ starting XV for their upcoming Challenge Cup campaign. The 30-year-old one-club man, who is renowned for his speed off the mark and his sniping at the base of the scrum, has played 68 European Cup games in 12 seasons, but this will be his first Challenge Cup campaign.