John Obi Mikel scored his first Barclays Premier League goal as Chelsea beat Fulham 2-0 at Stamford Bridge and won for the first time in a month.
Oscar's second-half strike and Mikel's first goal in almost seven years ended a four-match winless streak and extended manager Jose Mourinho's unbeaten Premier League home record to 63 matches with a first victory since the defeat of Aston Villa.
The 2-0 win means Fulham's 34-year wait for victory at Stamford Bridge went on to the relief of Chelsea, who responded from defeats against Everton and Basle by moving top of the table.
Defender Dejan Lovren's second-half header snatched a shock 1-0 win for Southampton at Anfield and consigned previous leaders Liverpool to their first defeat of the season.
The Croatian rose highest to head home Adam Lallana's 54th minute corner despite Steven Gerrard's desperate attempts to prevent the ball going over the line.
Mauricio Pochettino's men had goalkeeper Artur Boruc to thank for reaching the interval on level terms after he produced a stunning save to deny Gerrard from a 22nd minute free-kick, and also pulled off a fine save from Victor Moses.
Liverpool goalkeeper Simon Mignolet also impressed by keeping out a Lallana shot early in the second half but Saints kept pressing and looked more likely to add a second after Lovren's opener.
Mignolet produced a superb one-handed save to deny Daniel Osvaldo, then made three stops in quick succession after Luke Shaw surged into the box as the visitors claimed a deserved win.
Liverpool's loss left neighbours Everton as the only unbeaten team in the top-flight this season after Leighton Baines inspired a dramatic 3-2 win over 10-man West Ham at Upton Park.
Ravel Morrison put the Hammers ahead at the break from a heavily deflected drive, but Baines equalised just past the hour mark when he smashed an unstoppable free-kick past Jussi Jaaskelainen.
Mark Noble restored the Hammers' advantage from the penalty spot in the 76th minute after Kevin Nolan was up-ended in the box - but turned from hero to villain seven minutes later when he was sent off for a foul on Ross Barkley just outside the box.
Baines lashed home his second goal from the resulting set-piece - and substitute Romelu Lukaku grabbed the winner two minutes later when he headed home a Kevin Mirallas cross.
Stephane Sessegnon needed just 20 minutes to heap more misery on his former club as West Brom eased to a 3-0 win over Paolo Di Canio's struggling Sunderland at The Hawthorns.
Having left the Black Cats on transfer deadline day, Sessegnon refused to celebrate after bundling home a scrappy opener midway through the first period.
Liam Ridgewell fired home the Baggies' second on 76 minutes and the impressive Morgan Amalfitano completed the scoring with a strong drive in injury time.
Sone Aluko fired a stunning late winner for Hull as the Tigers twice hit back from behind to beat Newcastle 3-2 in a thriller at St James' Park.
Loic Remy's brace proved in vain for the Magpies and the Frenchman was left disappointed after missing a glorious chance to grab an equaliser in injury time.
Remy opened the scoring from close-range in the 10th minute before Robbie Brady drove the equaliser under Tim Krul just before the half-hour.
Remy put the Magpies back in front just before the break but Ahmed Elmohamady headed an equaliser three minutes into the second half, and Aluko won it for the visitors with a superb side-footed volley from the edge of the box in the 76th minute.
Libor Kozak came off the bench to earn the three points for Aston Villa in a 1-0 win over Norwich at Carrow Road.
Villa's hopes were hit by the withdrawal of Christian Benteke in the 27th minute with a hip injury - but his replacement Kozak took just three minutes to make his mark as he swept home a lay-off from Gabriel Agbonlahor.
Villa goalkeeper Brad Guzan had saved a seventh minute penalty from Robert Snodgrass after Ciaran Clark was penalised for a handball, and also denied Canaries debutant Gary Hooper by tipping his late header over the bar.
Saturday's Premier League Results
Norwich 0-1 Aston Villa
Liverpool 0-1 Southampton
Newcastle 2-3 Hull
West Brom 3-0 Sunderland
West Ham 2-3 Everton
Chelsea 2-0 Fulham