TONIGHT's Melbourne v Brisbane showdown is a virtual selection trial between Karmichael Hunt and Billy Slater for the full-back's jersey in May's Centenary Test. The Australian understands that selectors have met already to discuss the full-back position because of the talent available in the competition. Manly's Brett Stewart is the incumbent having replaced the injured Hunt in last October's 58-0 drubbing of New Zealand in Wellington. But until his hat-trick of tries against the Warriors on Monday night, Stewart had not fully warmed-up for season 2008. The Cowboys' Matt Bowen, who is a late withdrawal against Parramatta on Saturday night, is thought to be too small to take on the might of the Kiwis forwards, while former Australia full-back Anthony Minichiello (Roosters) is yet to reproduce his best form. The race is between Hunt and Slater with their respective performances tonight (Friday) going a long way to helping selectors decide who plays against New Zealand on May 9 at the SCG. Hunt and Brisbane captain Darren Lockyer are back for the match against Melbourne, although their return has been offset by news Justin Hodges (hamstring) is in doubt, while hooker PJ Marsh (ribs) is out. Marsh, who fought his way back from a broken neck to re-establish himself as one of the game's best dummy halves, has been grounded this week by, of all things, a sneeze. The rugged utility is still awaiting the results of scans on his ribs to determine the extent of the damage caused by the faux pas, which occurred as he was driving to Brisbane's Red Hill training base on Monday. A crack was discovered in the side of his ribs on Monday evening after a sneeze caused searing pain. "The doctors said there was obviously something there and just that action of sneezing obviously aggravated it," Marsh said. In his first year at the Broncos, the former Parramatta and Warriors rake has been in sensational touch, proving with his work around the rucks that he is more than capable of filling the hooker-utility role vacated by Shaun Berrigan.