Russell was drafted in by the reigning Formula 1 champions after Lewis Hamilton had tested positive for Covid-19 ahead of the Sakhir Grand Prix.
The highly-rated Briton then delivered a sensational display across the weekend, qualifying just 0.026 seconds behind Valtteri Bottas before he was then on course for victory until robbed by a botched pit stop and late slow puncture.
Ahead of the season-ending race in Abu Dhabi, Mercedes had been unsure whether Hamilton would be fit to compete before announcing on Thursday evening he would return to the W11 with Russell heading back to Williams.
Although conceding Russell may be "a bit disappointed" to return to Williams rather than in a potential race-winning seat this weekend, Roberts said: "It's great to have him back. It feels like he's come home for the weekend, which is really nice.
"He came back in a fabulous place. He had a fabulous weekend last weekend. I'm sure he was a bit disappointed inside but we gave him a really warm welcome back, we're really genuinely pleased to see him."
Compared to a week ago when Russell topped the timesheet in FP1 ahead of the Sakhir GP, it was back down to earth for the 22-year-old in the opening practice run at the Yas Marina Circuit where he finished 16th, three seconds adrift.
But a complimentary Roberts said: "His programme went to plan. We were running a few rakes to test stuff for next year but he tapped into the car really quickly. I'm sure maybe on that first lap he was trying to find his braking points again in our car.
"But he didn't put a foot wrong, he got everything out of the car we expected, and we're looking forward to a good weekend again."
Such was the pace of Russell across his weekend with Mercedes that questions were asked as to whether he could make the step up to the championship-winning outfit in 2021 despite having a Williams contract in place for the year.
Confirming the situation, Roberts added: "Definitely inside we have known for quite some time what a talent he is and last weekend he got the chance to show it on a world stage and we're really pleased he got that opportunity.
"We've got Nicholas [Latifi] and George signed for next year and the path we're working on right now is just to make sure that we can give them the best possible car next year."
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