BARCELONA, Spain -- Lewis Hamilton says he has noticed an improvement in the performance of his teammate Valtteri Bottas ever since one of his engineers crossed sides in the Mercedes garage.

A reshuffle of Mercedes engineering staff was prompted when Bottas' former race engineer, Tony Ross, left the F1 operation at the end of last year to head up the engineering team on Mercedes' new Formula E outfit. Hamilton's former performance engineer, Riccardo Musconi, replaced Ross over the winter and has already overseen two victories and two pole positions for the Finn.

Speaking about Bottas' improved performances in 2019, Hamilton said he suspects Musconi's arrival on Bottas' side of the garage has offered a "helping hand".

"This year he [Bottas] has my No.2 engineer, so my second engineer for the last two years has been promoted to head engineer for him, and so that will be a nice helping hand and he is learning a lot from that," Hamilton said. "That's to be expected, the little bit of a step he's taken.

"I've got a new [performance] engineer and we are working really well together but it takes time to build relationships with people and to continue to grow. So when you take one element away, whatever element you take away, initially it's not as strong as something you have built over six years.

"We are building back to being stronger and trumping that. It's only been four races, so watch this space."

When asked what had changed for Bottas this year, he added: "You could say he looks a little bit more focused than he was in previous years. The things he is doing on track, which my engineer has obviously encouraged him to do, the things I was doing with settings he is now doing and he has definitely moved in the right direction there. Otherwise he is still the strong Finn that he has been before."

Valtteri Bottas has taken two pole positions and two victories this year. Mark Thompson/Getty Images

Bottas also confirmed the changes to his engineering team had opened up new setup ideas and performance.

"Actually I have a completely new engineering team, a new race engineer and also a new performance engineer," he said. "For sure when you have new people around that makes you think at things differently, it opens new routes on your way of thinking about the set-up, opens new directions and it has started really well. We've been learning a lot, as an engineering team all the time, and it's getting better and better. So, so far, so good."

At the last round in Azerbaijan, Hamilton and Bottas went wheel-to-wheel in the opening few corners of the first lap before Bottas came out ahead before Hamilton piled the pressure back on his teammate in the final few laps.

Speaking after the race, Mercedes team principal Toto Wolff said the situation reminded him a little bit of the toxic rivalry between Nico Rosberg and Hamilton, which created a rift in the team between 2014 and 2016. But Hamilton is convinced his relationship with Bottas will not go the same way.

"There are things that happen in the background that you won't know about and I don't really feel this is the place to talk about it, but there are things that happen that you just don't know," he added. "So when he [Wolff] mentions glimpses of that it's because he has seen a glimpse of it, but what's really important is that will pull together as a team. We have discussed it and hopefully rectified it so that won't spring up again.

"What happened before was that an individual continued to go down that route and that's not what we have here. We have a really great energy in the team and we have an agreed set of rules so that we do finish the races one-two and we play supporting roles either way.

"I truly believe it is the best pairing in terms of that respect, and how we deliver each weekend, it is better than any other team has ever had or currently has."

Asked to elaborate on what had happened in the background, Hamilton added: "Nope, it's all internal and not for the public domain. But as I said, everything is great within the team and the respect is still there. We will continue to push on and we won't have any problems. Don't expect to see what you have seen in the past."