Koeman is preparing for his first game in charge of the Saints, which comes against Brendan Rodgers' side at Anfield on Sunday.
Liverpool boss Brendan Rodgers has splashed almost £50m on new talent, including Southampton trio Adam Lallana, Rickie Lambert and Dejan Lovren.
Koeman signed Shane Long and Florin Gardos on Thursday to replenish his squad following a summer exodus of high-profile players.
He said: "Luis Suarez is a great player who scored a lot for them.
"But if you look through the Liverpool squad they have so many good football players. Liverpool is much stronger than last season.
"It's a great start for us to play away against Liverpool, we know it's a tough one but everybody starts on nil.
"The players know how to win at Anfield, We are ready to play."
Koeman insisted he is pleased with his current squad, adding: "Everybody has to show their qualities and ambitions and I believe we are very well prepared.
"I know what team will play on Sunday. I know everything, but I have to tell first to the players what we like to do."
Watch Liverpool and Southampton start their Premier League season live on Sky Sports 1 HD on Sunday - coverage starts at 12:30pm.