despite wanting to represent england at international level, an opportunity to represent jamaica arose early in november 1997 following their qualification to the 1998 fifa world cup. manager rené simões had called up a number of english-born players such as deon burton, robbie earle, paul hall, and fitzroy simpson in the qualification matches and wanted frank to join the group. sinclair stated, "i was playing the best football of my career and was still not involved with england. jamaica came up and i thought an opportunity like that might never happen again so i took it." he was called up to the squad for the 1998 concacaf gold cup held in february, making his debut in the opening group stage match against brazil which finished in a 0–0 draw at the miami orange bowl. he played in the remaining two group stage games as jamaica qualified for the knockout stage with wins over guatemala and el salvador. jamaica were knocked out in the semi-finals due to a 1–0 golden goal defeat to mexico, and finished in fourth place overall as they lost to brazil in the third place play-off match. sinclair made a total of five appearances in the tournament.