Spurs avoided a fourth successive defeat on Thursday as they claimed a 2-2 draw in Portugal despite being without 11 first-teamers in the second leg of their Europa League last-16 tie.
They failed to overturn a 3-1 deficit from the first leg but they were only denied a victory by a last-gasp penalty and return to White Hart Lane with renewed optimism.
"Listen, the expectancy is very high at the club and with every right, a lot of money has been spent by Tottenham," said Sherwood.
"It counts for nothing, it's all about doing the job on the pitch and Southampton have got a lot of internationals.
"They've built a good squad and a good way of playing. They've got a lot of
England internationals who are going to be representing our country in the World Cup. It's going to be a tough game."
Eighth-placed Southampton were the opponents when Sherwood managed his first Premier League match in December with Spurs winning 3-2 at St Mary's.
Saints head into the match three places and eight points worse off than Tottenham, yet they are considered one of the season's most impressive performers.
Mauricio Pochettino's side have earned many plaudits for their performances and focus on home-grown talent, with academy graduates Luke Shaw and Adam Lallana strong contenders to make England's World Cup squad.
"It's a good model," Sherwood said. "It's a completely different model to Tottenham, as much as we want to bring our boys through.
"Our boys have to be at a level of playing Premier League to Champions League. Southampton have had the benefit of their players being developed from League One to the Championship to now. So it's good.
"Now is a test for them. How many can they deliver into the Premier League straight away?"
Watch Southampton take on Tottenham at White Hart Lane on Sky Sports 1HD at 1.30 pm on Sunday.