On paper, Red Bull looks unstoppable right now. Max Verstappen has taken 85 of a possible 86 points over the last three races, and Sergio Perez has backed him up to give the team a return of 140 from the maximum 147 available.

Those results have included two one-twos, the second of which came on Sunday in Barcelona where Charles Leclerc retired and Carlos Sainz failed to get on the podium, allowing Red Bull to assume the lead in the constructors’ championship as well as Verstappen moving top of the drivers’ standings.

But fortunately, motor racing doesn’t take place on paper. And unlike Imola, where Red Bull looked the class of the field, this latest one-two in Spain comes with plenty of warning shots that will be playing on team principal Christian Horner’s mind.

The first of them was fired by Leclerc on Saturday, when he ruined his first qualifying attempt in Q3 by spinning at the chicane. Leaving a tiny bit more margin at that corner, Leclerc then duly went over 0.3s clear of Verstappen, who never got the right of reply due to his DRS issues but was facing a tall order to overhaul the benchmark.

Given Leclerc had to get a lap in or start 10th, there was likely even more time on the table, and Ferrari’s one-lap pace was pretty ominous. But Friday had seen a level of degradation that would have given the championship leader very little hope of fighting with Verstappen, as Red Bull looked comfortably quicker on a race run as a result.

So Ferrari made changes overnight and tried them out on Saturday in FP3, getting the impression it had improved the situation. Leclerc’s first stint proved that it certainly had, as he managed to make his new soft tires last for 21 laps at the start of the race, some 33% longer than Pirelli had predicted would be the maximum early on.

That he did it while pulling away from Verstappen with such ease was another ominous sign.

“We had very good degradation,” Leclerc said afterward. “On the soft tire we could do quite a few more laps compared to them. So overall I think we had this race under control.”

Of course, none of that pace was worth anything once the Ferrari lost power and forced Leclerc to the garage, but prior to that there had seemed to be little hope of Red Bull overhauling the leader.

An unusual handicap at the back of Verstappen’s car in Spain. Mark Sutton/Motorsport Images

And that was in part due to reliability issues of Red Bull’s own. The DRS problem from Saturday was always going to be a concern, but then Verstappen didn’t emerge from the garage and leave the pit lane until he had five seconds to spare heading to the grid, meaning he had to drive straight to his starting spot and not get a true feel for the car’s balance or carry out a practice start.

At the time, I interviewed Horner on the grid and he first said there were no issues, before later claiming it was just a few checks on the DRS that the team wanted to do. But other observers suggested the DRS wasn’t worked on, and regardless Red Bull could have done that on the grid.

Instead, the suspicion was the team was struggling to get the fuel in Verstappen’s car at a legal temperature, something suggested by Ferrari team principal Mattia Binotto, too.

“Obviously I cannot know what was happening at the time there,” Binotto said. “I can imagine it was down to the fuel temperature in the tank that needs to be maximum 10 degrees (Celsius) below the ambient. I think per regulations it should be at all times during the event, so not only when the car is going out but in the garage itself as well.

“I don’t think a fire or trying to heat up a fuel tank would be sufficient because the fuel should be at all times not more than 10 degrees. For me it’s difficult to understand that they were maybe heating up the fuel through a fire, because it would not explain it because it should be at all times. But I can only trust the FIA and I’m pretty sure they are comfortable — they checked, and maybe that’s not the right explanation as well…”

Horner later claimed it was the DRS that kept the team in the garage, adding to the intrigue, but despite Binotto continuing the needle I wrote about last week, as the Italian said the car passed FIA checks and its only failure turned out to be the DRS again during the race. It was an issue that for a spell looked like hurting Red Bull’s hopes of victory given George Russell’s sensational defending, but that was the wrong Mercedes to look at when it comes to the looming threat.

Hamilton’s storming comeback in Spain suggests Red Bull has another team likely to take the fight to its drivers for the rest of the year. Carl Bingham/Motorsport Images

Lewis Hamilton’s race pace was remarkable after his first-lap puncture, allowing him to go from more than 58 seconds behind Verstappen at the end of lap eight — the final lap before Verstappen’s off-track moment — to just over 39 seconds adrift by lap 62, when a reliability concern also forced Hamilton to slow and give up fourth place.

Neither driver had clean races, as both dealt with incidents, traffic and strategic changes, but for Hamilton to take nearly 20 seconds out of Verstappen in race time means he would at the very least have been a major threat for second place and perhaps Leclerc’s biggest rival had he avoided contact with Kevin Magnussen on the opening lap.

It took six races to see the first real gains made by Mercedes but they were so significant it seems tough to believe Hamilton and Russell won’t be winning races in the remainder of this year.

Or if the race had played out cleanly for the top six, it could well have been Leclerc extending his championship lead with Mercedes preventing Red Bull and Verstappen from limiting the damage.

Of course, a one-two result is one that Red Bull will celebrate and be delighted with, but it won’t mask the fact that its main challengers appeared to get a lot stronger over the past weekend. What a fight we’ve got in store.