WPP chief financial officer Paul Richardson said that WPP, Publicis and market leader, US-based Omnicom, will begin to move away from their rivals in the coming years.
WPP is the number two-placed advertising holding company behind Omnicom, with Publicis in fourth place behind Interpublic.
However, despite holding the third spot Interpublic is seen as having problems that have seen it crash through financial scandal and client loss.
Earlier this week, it lost its grip on Samsung's $700m (£378.1m) global account, which was handled by its Foote Cone & Belding agency, and saw another client Revlon put its $120m account up for review.
Yesterday, Brand Republic reported how Interpublic's investments in Lowe Worldwide had led to a $310m write-off. The large write-off contributed to Interpublic reporting a loss of $600m for the first nine months of the year.
Interpublic has written off exceptional costs in excess of $3bn since 1999, of which $1.2bn related to overpriced acquisitions. In the past nine months, the company has been hit by $675m in write-offs relating to its motorsports business, which it has now exited completely, and a write-down of its investment in the German agency Springer & Jacoby.
Speaking at a Morgan Stanley investor conference, WPP's Richardson said: "Those big three will pull away and the gap will get wider. The rest have a lot of ground to make up."
For WPP, this year has been a story of huge wins. The Samsung victory came on top of HSBC's $600m global account and the €1bn (£700.9m) pan-European media buying account for Unilever, which went to MindShare.
WPP's other media network, Mediaedge:cia also, retained the £105m Deutsche Post World Net international media account this week alongside Vizeum.
It also won the battle for Grey, giving it an entree into Procter & Gamble and increasing its ability to maximise cost efficiencies.
There has even been talk that WPP might make a bid for Havas, the mid-sized French group, which has also been linked to Publicis.
However, Richardson said that WPP was busy integrating Grey Global into its business.
"We have our hands full with Grey and we have our hands full making sure HSBC and Samsung are integrated into our network. Those things are fact, the rest is speculation," he said.
Publicis CFO Jean-Michel Etienne echoed Richardson's comments, when referring to the Samsung pitch.
Although most of the account has gone to WPP, Samsung has left the way open to work with other agencies.
"There are obviously some winners and some losers in this market. If we look at the Samsung pitch, we don't know exactly who is the winner, but we know who is the loser: Interpublic," he said.
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