Nottingham Forest pulled off the biggest upset of the Premier League season so far, defeating Liverpool 1-0 at Anfield thanks to a stunning second-half strike from substitute Callum Hudson-Odoi.
Liverpool controlled much of the first half, with Luis Diaz striking the post in the 17th minute.
However, the home team struggled to connect in attack, with their play lacking its usual sharpness and missing several opportunities.
They were made to pay for their wastefulness in the 72nd minute when Anthony Elanga sent a superb crossfield pass to fellow substitute Hudson-Odoi, who cut inside and curled a brilliant shot past Alisson.
Despite having won their first three league games under Arne Slot without conceding, Liverpool appeared out of ideas as they tried to respond, with their best chance coming from a Virgil van Dijk header that went over the bar.