Liverpool failed to win for the third consecutive Premier League game as Danny Ings’s second-minute goal earned Southampton a 1-0 win at St. Mary’s on Monday.
The English champions remain top of the table on goal difference over Manchester United, but have now played a game more than the Red Devils.
Southampton are only four points off the top as they moved up to sixth in a tightly bunched division with just seven points separating Liverpool from West Ham in 10th.
A famous win continued a fine season so far for the Saints, and a the size of the achievement was reflected in tears of joy from manager Ralph Hassenhuttl at full-time.
A first league defeat in three months may hasten Liverpool’s search for a centre-back in the January transfer window.
Without the injured Virgil van Dijk, Joe Gomez and Joel Matip, Klopp started two of his first-choice midfielders from their title-winning campaign, Fabinho and Jordan Henderson, together at the heart of his defence.
Southampton had not scored in their last three games to temper their hopes of a push for European football, but took just two minutes to break the deadlock in style through former Liverpool striker Ings.
Liverpool did not deal with James Ward-Prowse’s angled free-kick into the box and Ings perfectly hooked his shot over Alisson Becker into the far corner.
Southampton had key absentees themselves with goalkeeper Alex McCarthy missing due to a positive test for coronavirus, while Oriol Romeu, Jannik Vestergaard and Che Adams were out injured.