Daniel Ricciardo's victory in Monaco confirmed it will be a three-way battle for the Formula One title, according to championship leader Lewis Hamilton.
Despite struggling with a mechanical issue, Ricciardo successfully nursed his Red Bull around the street circuit to seal his second win of the season.
Both Mercedes' Hamilton and Sebastian Vettel of Ferrari have also triumphed twice already this year, with the former 14 points clear in the overall standings after finishing third in the principality.
Yet Ricciardo's performance in Monte Carlo - coupled with a potential upgrade by Red Bull to their engine - suggests the Australian could yet close the gap on the leading pair.
"It definitely is a three-way fight," Hamilton told the F1's official website. "Ferrari, I think, are still the strongest.
"Their car was quick [in Monaco], their car was working quite well through the whole season so far and they have dropped the ball a few times and we've capitalised on that so we are further ahead than we would be if everyone had done the same job, if you know what I mean.
"But I still feel they're the strongest and Sebastian has been doing the strongest job. But it is a three-way battle.
"I think Red Bull potentially have got an upgrade coming at some stage, engine-wise I think at the next race, so it will be interesting to see their performance and they will continue to get stronger through the year.
"So hopefully, while maybe the race [in Monaco] was not the most exciting, it's great for the fans to see this battle that we have.
"I'm telling you, we're doing everything we can to win the race - and then the Red Bulls win it, then the Ferraris win it and then we win. It's great to have that. I personally love it and it's challenging me more than I can express."
Ricciardo's contract with Red Bull expires at the end of the year, but Hamilton - who is also set to be a free agent for 2019 and beyond - feels his fellow driver should think carefully before moving elsewhere.
"At the moment [Ricciardo] is pretty much the lead driver in that team so it's not a bad place to be," the four-time world champion added.
"If at some stage Red Bull get an engine they're going to be even closer in the mix with us, and there is still a long, long way to go [this year] obviously. Who knows? They could win many more races.
"So I think he's just got to keep his head down, keep doing what he's doing, but he should definitely have a contract on his table and he should have his options ready."
