Jean-Laurent Bonnafe's rise to become chief executive of French bank BNP Paribas was perfectly scripted and the bespectacled rugby fan knows the bank better than anyone after a decade hammering its acquisitions into shape.

Outwardly shy 50-year-old Bonnafe was flagged back in February as the replacement for the flamboyant Baudouin Prot, who steered the bank through the financial crisis and now takes the chairman's seat from Michel Pebereau.

Taking over the day-to-day running of the biggest bank in the euro zone at the height of the crisis in the region will test Bonnafe's improvisation skills.

He will need to juggle sweeping asset sales, job cuts and a pullback in lending in response to regulatory demands for banks to hold more capital as a buffer against future downturns.

For the ex-BNP banker who first hired him in 1993, Bonnafe's past experience and his time spent working under Prot and Pebereau, mean he is up to the challenge.

I put great trust in a trio of men: Michel Pebereau, Baudouin Prot and Jean-Laurent Bonnafe. If the first two picked the third to take charge of the bank's future then I'm sure it's the right choice, Ervin Rosenberg told Reuters.

Bonnafe will be entirely able to meet the difficult task ahead of him.

EMPIRE-BUILDER

After first looking after BNP's big corporate clients like L'Oreal and Saint-Gobain , Bonnafe was groomed to work alongside Prot and Pebereau, planning and integrating big acquisitions as the one-time state-owned lender sought to become the JP Morgan of Europe.

Those who know Bonnafe, an engineer by training, say he is fiercely intelligent and prudent, having followed closely in the footsteps of risk-focused former civil servant Pebereau.

Bonnafe played a key role in BNP's three big purchases -- Paribas in 1999, Italy's BNL in 2006 and Belgian crisis victim Fortis in 2009 -- and came to be known as an operations man who could also think strategically and deliver on cost savings and revenue growth.

While BNP's empire-building helped it survive the 2008 financial crisis, it has now put it in the front line of the current turmoil, with investors using its shares as a proxy for the fortunes of the single currency bloc.

BNP is my favourite of the French banks ... But just like all the major European banks, the risks facing it are large and diverse and difficult to quantify, said Erin Davis, an analyst at Morningstar. These companies are largely unmanageable.

With a AA- rating from Standard & Poor's, BNP is seen as more robust than domestic rivals Credit Agricole and Societe Generale , which have weaker capital ratios and patchier histories of managing risk.

However it too is having to reduce lending and drastically change its funding model at a time when liquidity is rare and costly.

BNP has a lot to do ... It needs to carry out its deleveraging plan and it needs to refocus its activities, said Yohan Salleron, a Paris-based fund manager at Mandarine Gestion.

NO SURPRISES?

BNP insiders say the bank has been preparing for quite some time for the changes afoot in the sector.

BNP Paribas has been extremely active in preparing for the new regulatory environment in terms of balance sheet, capital and liquidity, said a spokeswoman for the bank.

Bonnafe has picked well-known company men to serve as joint chief operating officers below him, in keeping with the smooth handover of power -- a contrast to recent internal dramas at Switzerland's UBS or Germany's Deutsche Bank .

But that does not mean there will not be surprises ahead.

Given Bonnafe's knack for spotting opportunistic acquisitions, some say BNP's strategy of keeping risk low while waiting for the right time to pounce on a rival could lead to an acquisition -- even in an environment when big banks like BNP are being cut down to size by regulators.

The surprise would be acquisitions, that's what he made his name on, said a London-based analyst. Given his background that would be the most likely corporate action he might unveil.

Others say Bonnafe's arrival may free him from the red lines drawn by Prot, including the question of raising capital to meet tougher rules under the Basel III regime's planned tough medicine for the banking sector.

Prot reiterated on Monday the bank would not raise capital to meet new requirements. Some analysts and M&A bankers, however, say that if the market turmoil eases and appetite for assets being sold by banks remains poor, raising capital on the market will be a serious option for European lenders.

(Additional reporting by Matthieu Protard; Editing by Helen Massy-Beresford and Alexander Smith)