Grey has limited options. Following its stated intent last week to keep the company intact rather than sell it piecemeal, it has effectively ruled out the option of selling to a private equity group.
Earlier this month, Publicis ruled itself out of the race for the entire company, joining the ranks of other uninterested parties, including Omnicom and Dentsu.
However, the interest from Havas could provide Grey's global chairman, Ed Meyer, with the right conditions for a sale with two bidders driving the price for the company up.
It would mark the second time Havas and WPP have gone head to head in a battle over a smaller company. In 2001, the two fought for the media group Tempus, won eventually by WPP.
Grey has rejected approaches to sell its network in the past, leading to speculation that, given the current lack of interest, it misjudged the market.