On day three, Leclerc himself put in the fastest time of the day, but the 1:30.322 was not enough to pip Sainz to the honour of having the fastest time of testing overall.
Speaking with the media, the Mercedes driver said: "Red Bull are the favourites and definitely a step ahead of everyone else. That was to be expected."
"This iteration of regulations there is definitely a sweet spot for all the teams. You want the car as low as possible, but you can't go too low in case you're bottoming out or you cause bouncing, which is still there in the background for some of the teams.
"Red Bull are already in that sweet spot, but hopefully, we can close the gap. But it is going to take a lot of hard work to do it."
Lewis Hamilton's soon to be team-mate Leclerc added: "In terms of feeling, our car feels a lot better than last year. My initial feeling is that Red Bull remain quite a bit ahead."
Verstappen wants more from rapid RB20
Reigning world champion Verstappen focused more on long runs during pre-season testing, completing 209 laps of the Bahrain International Circuit during his one-and-a-half days of running.
However, despite not setting a hot lap on soft tyres, Verstappen nonetheless sent an ominous warning to his rivals. The Dutchman set the fourth-fastest time of day three on the mediums, with his time just over four-tenths slower than Leclerc's.
“I think overall it’s been really good, I couldn’t have really wished for more; I was actually wishing for less laps,” joked Verstappen during Friday’s FIA press conference.
“But, no, I did a lot of laps, everything went well, the balance was very nice, we tried to put a few things on the car. Also, for me, to understand and to move forward.
"And yeah, completed the whole programme without any problems. So, for me, that was a very good day.
"The team believes that with how the car is at the moment, that there is more potential to find, I guess, so that's now up to us to unlock.”
Whether that will translate into outright performance remains a different question. Currently, Red Bull seemingly remain the pacesetter, with Ferrari also showcasing good speed during the three days.
“Do I think we’ve taken a step forward? Absolutely,” Norris told media at testing.
“Do I think we’ve made a lot of things better? Yes. But you never really know at the end of the day where we stand comparing to others.
“I think we’re in a good position. We had a decent car at the end of last season. I definitely think we’ve taken some steps in the right direction, but I think [we're] still quite a long way behind Red Bull and a long way behind Ferrari still.
“So, plenty of work for us to still try and achieve but also plenty of things that we’ve learned over the last few days for us to implement before next week."
The Australian, now heading into his second season in the sport, completed 183 laps during the three days in Bahrain.
“I’d like to think we are somewhere towards the front of the grid," reflected Piastri in a post-testing press conference.
"I certainly don’t feel at the moment we are in a position to challenge Red Bull, I’m not sure anyone on the grid particularly feels that way at the moment.
“Without jumping to very early conclusions just with past results around Bahrain specifically, Bahrain is not on paper a great circuit for us, so it’s a bit hard to have a read, especially after just two days of testing.
“It’s a bit hard to tell, and I expect it to chop and change quite a lot depending on the circuit characteristics. It’s very hard to get a read on where everyone else sits at the moment, the only pretty clear conclusion from everyone is that Red Bull are looking strong.