The Belgian international defender joined the Saints on a season-long deal from Spanish champions Atletico Madrid earlier this summer.
With Alderweireld likely to make his debut for Southampton against Newcastle United this weekend, the 25-year-old believes that English football will provide him with a sterner challenge than Spain's top flight.
"The football requires more from you physically than in Spain," he is quoted as saying by Sky Sports News. "The Premier League is also changing. I have four years in a row in the Champions League and have played in the World Cup, I know what excellence means."
Alderweireld made 19 appearances last season as Atletico won the Spanish title and reached the Champions League final.