Asked recently if - in the interests of continuity - Romain Grosjean will definitely be retained next year if Kimi Raikkonen departs, team boss Eric Boullier answered simply: "Yes."
So that leaves only the cockpit currently occupied by the Ferrari-bound Finn Raikkonen to fill.
The candidates are Hulkenberg - the impressive German who after moving from Force India last year is now seeking to jump from struggling Sauber - and the experienced Ferrari refugee Massa.
Brazilian Massa, 32, might have the edge.
According to O Estado de S.Paulo newspaper, Frenchman Boullier said recently that, "In 2014, experience will be more important than speed".
He is referring to the move from the current engine rules to next year's regulations surrounding the turbo V6s, which according to most of the sport's technical insiders is perhaps the biggest shift in the history of F1.
That is why, on the face of it, while the younger but hugely promising Hulkenberg perhaps should be the favourite, Massa's vast wealth of experience might have him in pole position for the seat.
A source close to Boullier told Brazilian correspondent Livio Oricchio: "The chances are 50 per cent apiece for Hulkenberg and Massa."
Oricchio said the prize on offer is a two-year contract with options.
And there may be another factor counting in Massa's favour -- money.
While definitely not a traditional 'pay driver', Massa would bring some weighty support to Lotus in the form of his well-connected manager, Nicolas Todt.
The son of FIA president Jean Todt, Nicolas has - according to Italy's Autosprint - already brought a sponsor to Lotus in the form of Swiss watchmaker Richard Mille.
Massa's continuity in F1 is also backed strongly by Bernie Ecclestone, who fears the absence of a single Brazilian on the grid could affect the success of the crucial Brazilian market, and the popular Brazilian Grand Prix.
"It would be surprising if (Ecclestone) has not talked to Boullier and (Gerard) Lopez about his preference regarding the choice between Hulkenberg and Massa," said Oricchio.
And Felipe Massa says he is in negotiations with Lotus about a 2014 race drive.
Massa will be replaced by Kimi Raikkonen at Ferrari next season, opening up the possibility of a straight swap next year. Lotus has confirmed it is in talks with a number of drivers about 2014 and will make a decision "shortly".
Massa said Lotus appeals to him as the most competitive option remaining on the grid.
"We are negotiating," he told Globo Esporte. "In my opinion, Lotus has a competitive car, which is what I want.
"We are having many conversations to try to find a way, not only for me but for Lotus, to continue with a good car."
Massa revealed he had also talked to McLaren, but said Lotus is currently his best option.
"I've had contact with McLaren but I cannot judge, it's hard to say," he added. "With Lotus, the contact was very good."
Last week Massa's manager Nicolas Todt told Canal Plus that Massa is determined to land a deal at a competitive team next year.
"He never would go to a smaller team to be second driver," Todt said. "We need to find a car that can challenge at the front in F1. The best place available is undoubtedly the one left by Raikkonen at Lotus."