While 2012 will be a bumper year for advertising, 2013 could be more troubled, Sir Martin Sorrell, chief executive of WPP, the world's largest advertising company, warned Friday.
WPP cut its outlook for the full year for the second time in two months on Friday, citing slowing growth in the US and concerns about the euro zone.
Still, Sir Martin sounded an optimistic note about the outlook for the rest of the year and 2012, which is set to be a bumper year for advertisers with the US Presidential election, the London 2012 Olympics and the 2012 UEFA European Football Championship.
"People look at 2012 and think it's going to be awful, but I think we'll muddle through eventually in Europe," he told CNBC Friday.
"The rubber hits the road after the November election in the US. 2013 is what I'm worried about."
Asked about the euro zone deal agreed on Thursday morning, he said: "The devil's in the detail and there were so many in principle agreements I've become a bit cynical about it.
"The biggest issue we face in the world is the US economy, that is the key."
Third quarter organic revenue growth at WPP rose by a slightly worse than expected 4.7 percent, compared to average analyst forecasts of 4.9 percent.
Sir Martin said that the results were "in line with where we want to be" and give the company opportunities for margin expansion.
Online advertising is the biggest growth area for the company at the moment, while newspaper advertising continues to fall.
"Don't underestimate the power of Google or online advertising," Sir Martin said. "The primary driver is not TV advertising which has been reasonably buoyant, it's the online activity."
WPP, which moved its base to Ireland from the UK when the British government raised corporation tax on earnings made outside the UK in 2008, is planning to move back to London in late 2012 or early 2013.
Sir Martin said that the British government had been "very responsive" to concerns about the legislation.