Toto Wolff needs 'more proof' from Mercedes upgrade to 'feel warm and fuzzy'

Mercedes team principal Toto Wolff has conceded he needs "more proof" that the upgrades on Kimi Antonelli's car are working before feeling content about the situation.

Mercedes unveiled an update package on the W17 at last weekend's Bahrain Grand Prix in Malaysia, leaving many of their F1 rivals fearful the team would take another leap forward after dominating this season.

Instead, Mercedes were not as competitive as had been expected, with fingers being pointed at the conditions and the abrasive asphalt at the Sepang International Circuit.

Heading into this weekend in Singapore, and knowing George Russell would be hit with a major power unit penalty, the team has so far run two different packages, reverting to the spec on the Briton's car that helped him dominate in Azerbaijan, whilst leaving title-leading team-mate Antonelli on the new spec.

After first practice, Mercedes then placed the old front wing on Antonelli's car, believing it to be a step forward.

In sprint qualifying, Russell and Antonelli qualified second and seventh; for the grand prix, Antonelli was fourth fastest, Russell sixth, although he will be demoted to the back of the pack.

Summing up the event so far as "complicated" given his team has "two different cars running", speaking to Sky Sports F1, Wolff added: "On Kimi's side, the update seems to have worked now.

"He and his engineers have dialled out the problems, and we got closer and closer. Eventually, we're missing a tenth and a half or two tenths, and that is at least positive for qualifying."

As to whether he was 'feeling a bit more warm and fuzzy' towards the upgrade, Wolff replied: "It will take more proof of concept until I'm feeling warm and fuzzy, but we will have more data tomorrow in the race."

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Wolff - 'I didn't think it was him'

Wolff at least hailed the performance of Russell in qualifying after crashing out of the sprint earlier in the day whilst leading at the end of lap one.

In wet conditions, Russell nailed his start off the line and surged past polesitter Max Verstappen in his Red Bull on the short run-down to Turn 1, only to then lose the rear of his car after running over a painted kerb as he turned onto the start-finish straight.

Wolff was stunned to see Russell make such a mistake, but at least pleased he recovered to execute a solid qualifying in a car not fully rebuilt.

"When I saw the yellow coming out, I didn't think it was him because I couldn't imagine that George would make such a mistake because it hasn't happened for a long time," said Wolff. "The last one was in Singapore, in the race with Lewis [Hamilton] maybe, so very, very unusual.

"Fair enough, the power kicked in at a moment where he didn't expect it, and he was on the white line. Running first is always tricky because you're looking at how fast you can go through the corners, so not at all like George, but anything can happen.

"The mechanics then did an unbelievable job in putting the car together, but maybe at the end, we didn't have all of the sensors on the car, and it didn't feel as good as it did before, but George did a really good job."