Manchester City loanee Sinclair scored his first goal since August 2012 in front of Sherwood, who was in the stands, as Villa beat Leicester 2-1 to reach the FA Cup quarter-finals.
Sherwood gave Villa a half-time pep talk when the score was 0-0 before Leandro Bacuna and Sinclair netted to clinch a last-eight spot.
Paul Lambert was sacked on Wednesday after Villa slipped into the Barclays Premier League relegation zone and Sinclair believes the atmosphere at Villa Park has improved, with Sherwood - appointed on Saturday until 2018 - already making a positive impact
"There was a lift, but I have only been here two weeks so I'm trying to take in as much as I can," he said.
"There is a lift from the fans and all we can do is concentrate game by game and take it into the next one.
"I'm looking forward as much as anyone else in the team to working with him (Sherwood)
Hopefully he brings something different and it rubs off on the boys and we win games."
Scott Marshall, Villa's first-team coach, took charge of the side against Leicester, although Sherwood was in the dressing room at half-time.
"He came in and made in a couple of points to the lads, a couple of bits and pieces for everyone
I thought the boys delivered that in the second half and were very good," said Marshall.
"He was there and there was good information to the group
There's a football knowledge there which comes with a lifetime in the game.
"He was in the dressing room before the game briefly, not a huge amount, but he introduced himself and wished the boys the best.
"The last three days have been pretty intense
I'd like to say I enjoyed the game but it's a good feeling to come out the other side."
Defeat, despite Andrej Kramaric's late strike, left Leicester with just top-flight survival to focus on.
Matty James was denied by Shay Given and Marcin Wasilewski hit the post in the first half.
They are bottom of the Premier League table with 13 games left and boss Nigel Pearson wants his side to find consistency.
"We need mental resilience, absolutely
With the players' technical ability they are only able to put on a show if they have the mental qualities to do that," he said.
"It's been suggested that it's easier to prepare against the bigger sides but I don't know
We've found ourselves in losing positions far too often.
"It was more or less the same side (from the defeat against Arsenal)
We can't replicate the performances and that's why our season is what it is.
"There were too many careless mistakes when we had the ball
We maybe should have been in front at half-time."
Source : PA
Source: PA