May 6 (GMM) Robert Kubica has been a standout performer of the 2008 season so far, former grand prix winner Eddie Irvine says.



The outspoken Ulsterman, famous for his role alongside Michael Schumacher at Ferrari in the nineties and subsequently with Jaguar until 2002, hailed 23-year-old Kubica's emergence as a consistent challenger to the Ferrari and McLaren runners this year.



"You have to say he has done a fantastic job to be close to those guys," Irvine, who is now 42, told Virgin Media.



Irvine believes Kubica, the first Polish driver to race in formula one, has the measure of his current teammate, German veteran Nick Heidfeld.



"But Heidfeld's never been a top, top driver in my opinion," he added.



Irvine said the recent Spanish grand prix was "boring", but praised the flawless performance of current pacesetters Kimi Raikkonen and Felipe Massa, today's Ferrari duo.



"McLaren now have some catching up to do, that's for sure," he said.