KANSAS CITY, Missouri, July 4 : Argentina advanced to the World Cup last 16 with a 3-2 extra-time victory over Cape Verde, but the reigning champions left the match with new doubts after being pushed to the brink by the tournament debutants.Cape Verde twice came from behind and exposed vulnerabilities in the South American team before defender Cristian Romero's header, diverted into the net by Cape Verde's Diney Borges, finally settled the contest.Coach Lionel Scaloni had warned that Cape Verde would be dangerous after drawing with Spain and Uruguay in the group stage, but few anticipated such resistance from a side making their first World Cup appearance.After a near-perfect group stage, with wins over Algeria (3-0), Austria (2-0) and Jordan (3-1), the narrow escape is likely to intensify