Renault says it was surprised that its main rival in Formula 1 this year turned out to be Haas rather than McLaren.
When McLaren signed a deal to switch to Renault from Honda for 2018, many expected that the Woking-based team would be fighting for podiums and even wins.
However, a fundamental aero problem with the team's MCL33 left it struggling for performance and its form fell away over the course of the season.
That left the way open for Haas to emerge as one of the surprises of this year as the American-owned outfit took the fight to Renault in the battle for best-of-the-rest behind the big three teams.
Reflecting on 2018, Renault F1 managing director Cyril Abiteboul told Autosport: "Frankly, there were some surprises, and there were some frustrations.
"I am a bit surprised having to fight against Haas for most of the season when I was expecting it to be against McLaren.
"Let's remember last year, when we announced McLaren, everybody told me 'you are crazy, you are going to be beaten by your customers'.
"We were very close to being beaten by a team that is a very new team, a young team, younger even than us, with a very different set up."
Abiteboul says he has no complaints with the job Renault did this year, but he wants to spend some time this winter having a deeper analysis about its performance.
"It was a good season, and we can be sure of the progress the team is making," he said.
"We should not undervalue the effort and the achievement after three seasons moving from P9 to P4.
"I am not great at history but you would have to go back quite far to see a team achieving such an improvement.
"Having said that, obviously, I need to dig a bit further, to see how it was achieved, the competitiveness level, the competitive environment, who is just behind, who is ahead, and how far they are ahead.
"This is where we need to take stock and look at that in the eyes and see how it can affect our plans."
Renault's biggest challenge will be in making a step forward for 2019, because the gap between the top three teams and the rest of the grid remains big.
"There is a big, big negative margin to the top teams, which is a source of concern," Abiteboul said.
"But when I look at the rapidity of our progress at the factory and in particular in the preparation of next year for both chassis and engine, I am saying, why not? It is possible.
"There are frustrations but overall I think we can be satisfied with what were the main objectives: first consolidate the team's situation, being more or less the best of the midfield, and [secondly] to be in a position to reduce the gap to the top teams, which will clearly be the target of next year."