Harlequins have already won the European Rugby Challenge Cup more times than any other club with their three successes but face a tricky quarter-final at English rivals Worcester Warriors on March 30, live on BT Sport and beIN SPORTS. Here are five of their main men. Mike Brown A member of the last Harlequins’ Challenge Cup-winning team in 2011, the 33-year-old full-back is still an important cog in Quins’ squad and has taken his tally of European appearances for the London outfit to 74 this season with his four in Pool 5 and his try total to 23 with scores against Agen and Grenoble. The England veteran has won 72 caps. Danny Care Another member of Harlequins’ successful 2011 Challenge Cup side, the 32-year-old only played twice in the pool stages, but those appearances came in the decisive last two rounds and featured a man-of-the-match performance in the 33-17 victory at Agen, plus a try against Grenoble. England's most-capped scrum-half now has 23 tries from 75 European games. Alex Dombrandt The powerful 21-year-old back-row forward has made a sensational start to his Harlequins career this season with 10 tries in 16 appearances, including three in four Challenge Cup games. The Wales Under-20 international has rapidly gained a reputation for his barnstorming runs, regular turnovers and astute offloads from flanker or No.8. Kyle Sinckler Sinckler’s game has taken off this season with some outstanding displays for Harlequins and England that have been notable for the tight-head prop’s astonishing tackle count and silky handling skills. The 25-year-old British and Irish Lion has only featured three times in the Challenge Cup so far this season but expect him to be more of a regular in the knockout phase. Marcus Smith Smith is only 20 but has already made 50 appearances for Harlequins, including 12 in Europe. The multi-skilled fly-half has been a key reason behind Quins topping Pool 5 with 49 points from a try, 13 conversions and six penalties from his six outings. His 90% success rate from the kicking tee has left the England Under-20 half-back joint third in the points-scorers' chart.