McLaren is expected to make a final decision on its future with Honda this week, with their relationship at breaking point after a run of unreliability and poor performance.

If McLaren decides it cannot continue with its current engine partner, and Toro Rosso elects to stay put with Renault, Honda would be forced out of F1.

Despite the uncertainty, Honda has been pushing ahead with an aggressive development plan that yielded upgrades at Spa and Monza.

"I'm still trying to make good performance to convince them [McLaren] but I'm not sure it will be enough," said Honda chief Yusuke Hasegawa. "We Honda never give up to keep this collaboration."

While the situation could have become a distraction for Honda's staff back at Sakura and Milton Keynes, Hasegawa believes it is having the opposite effect.

"It accelerating our development," he said. "It becomes motivational inside the factory."

Honda has taken confidence from the performance of the upgrades it has introduced in recent races.

"Since Austria, the spec 3 engine introduction, our development has accelerated and the rate of development is very good," said Hasegawa.

"We saw some performance gain with each upgrade so it's very encouraging."

McLaren-Honda tactically took engine penalties at Spa and Monza in a bid to be penalty free at the next race at Singapore, which features a track likely to suit the car.

"We have some confidence about competitiveness [at Singapore]," added Hasegawa. "We have already decided the current engine will go to Singapore.

"We may update some settings or engine settings but we cannot do a big update in Singapore."

When asked about the performance of the latest upgrade - spec 3.7 - McLaren racing director Eric Boullier said: "Any extra horsepower we take them.

"As Hasegawa said, on data we can see some improvement so I am happy with that."