Broken ribs have robbed Hong Kong of playmaker Chris McAdam, who will miss the second game in the Asian Five Nations Top Five competition against Japan on Saturday and probably the rest of the campaign, too. Flyhalf McAdam was hurt in the opening minutes of last Saturday's opener against the United Arab Emirates but it was thought that his injury was minor. Subsequent examination has confirmed the worst. "It was worse than we thought and his injury is a big blow," said head coach Leigh Jones. "Apart from his kicking and attacking game, Chris brings a lot defensively and we will miss him. But at the same time this gives an opportunity for Niall [Rowark] to step up." Rowark took over the goal-kicking duties with a competent display in the 53-7 win over UAE, but he will be required to bring his A game as Hong Kong try to stop the Japan juggernaut - they beat Philippines 121-0 in Fukuoka in their opener last Saturday. In a bid to bolster the defence, Jones has made five changes to the starting line-up. In the forwards tighthead prop James Cooper replaces Steve Nolan, Will Hunt comes in for Dan Watson in the second-row, and blindside flanker Alex Baddeley replaces Matt Stockdale. "These changes have been made with an eye on increasing the mobility of the pack," Jones said. In the backs, Ally Maclay moves from midfield to left wing where he replaces Seb Alfonsi, and his place at outside centre is filled by Dave Whiteford. Pete McKee takes over as scrumhalf from Kirk Munro. Jones has also called up a new halves combination on the bench, Charles Cheung and Mike Glancy, both of whom played in the Cup of Nations last December in Dubai. "We are still trying out what is our best mix and looking at combinations. We didn't have any warm-up game prior to this season's Asian Five Nations and there was always going to be changes on the card for the first two games," Jones said. Overcoming Japan, unbeaten in all five previous seasons in the A5N, will probably be mission impossible, admits Jones. "Japan is anyway a different ball game. The variance between UAE and Japan will be huge and it is almost like stepping into the unknown. Our goal is to see how far we can improve from our first outing," he said. HK Squad 1 L Wei, 2 A Harris, 3 J Cooper, 4 W Hunt, 5 C French, 6 A Baddeley, 7 M Lamming, 8 P Tauti; 9 P McKee, 10 N Rowark, 11 A Maclay, 12 S Megaw, 13 D Whiteford, 14 J Rees, 15 T McColl (capt). Reserves: 16 T Bolland, 17 S Nolan, 18 D Watson, 19 M Stockdale, 20 C Cheung, 21 M Glancy, 22 S Alfonsi.