Honda F1 boss Yusuke Hasegawa believes the Japanese manufacturer can continue its rate of progress and catch Renault by the end of the season.
Following appalling reliability and performance from the outset of the 2017 season, the McLaren-Honda partnership found itself in crisis and questioning its future.
But recent progress by Honda has lifted both performance and McLaren's spirits, with the Woking-based outfit scoring a double-points finish in Hungary just before the summer break.
Hasegawa is confident further improvement is on the cards as it puts Renault in its line of sight.
"I think we can keep the same ratio of the increasing of the power but it is difficult to catch up Mercedes or Ferrari," Hasegawa told Motorsport.com.
"I really want to move ahead of Renault in terms of performance before the end of the season.
"I can see that on the data. I will not tell you the number, but we are closing the gap."
Hasegawa felt somewhat relieved by McLaren's positive race weekend in Hungary which was followed by a trouble-free two day test at the venue last week.
"I'm glad we were able to show some results," said the engineer.
"We did not see any problems (in Hungary) so it was the first time that I was not worried about finishing the race.
"There is no doubt that we would like to continue to cooperate with McLaren. I think that with better performance we will continue to work together," he added.