Liverpool crashed to a miserable 3-0 defeat at West Brom in Brendan Rodgers' first Premier League match as Reds boss, while Arsenal started life without Robin van Persie with a dour 0-0 draw against Sunderland on Saturday.
Rodgers took over from Kenny Dalglish after Liverpool finished eighth last season, their worst final position for 18 years, and on the evidence of a shocking result at the Hawthorns the former Swansea manager still has plenty of work to do.
Rodgers, who gave debuts to new signings Joe Allen and Fabio Borini and left unsettled striker Andy Carroll on the bench, might have feared the worst when he saw Zoltan Gera blast Albion into the lead with a stunning 43rd-minute strike.
It was a sweet moment for Albion manager Steve Clarke, who was sacked by Liverpool at the end of last season after spending 18 months at Anfield as Dalglish's assistant.
Pepe Reina kept Liverpool in the match when he saved Shane Long's woeful second half penalty after Reds defender Daniel Agger was sent off for a professional foul.
But Albion won another penalty in the 64th minute and this time Nigerian striker Peter Odemwingie stepped up to blast home.
And Romelu Lukaku, on loan from Chelsea, rubbed salt into Liverpool's wounds when he marked his West Brom debut with a 77th-minute strike.
Arsenal manager Arsene Wenger must have been concerned that the Gunners failed to break down Sunderland at the Emirates Stadium in the first game since Dutch striker van Persie's £24 million move to Manchester United.
Wenger gave debuts to Germany striker Lukas Podolski and Spain midfielder Santi Cazorla, while French forward Olivier Giroud, another new signing, came off the bench.
But the new boys were underwhelming, with Giroud missing the best chance of the afternoon.
West Ham enjoyed a winning return to the top flight as Sam Allardyce's side beat Aston Villa 1-0 at Upton Park in Paul Lambert's first game as Villa boss.
The Hammers, promoted via the Championship play-offs, took the points when Kevin Nolan sidefooted home in the 40th minute from Ricardo Vaz Te's assist despite Villa claims the West Ham striker was offside before he laid on the goal.
Swansea manager Michael Laudrup savoured a five-star debut as new boy Michu inspired a 5-0 demolition of QPR at Loftus Road.
Michu, signed by Laudrup from Rayo Vallecano for £2 million, took just eight minutes to score and the Spaniard struck again in the 53rd minute.
Nathan Dyer netted in the 63rd and 71st minutes and Scott Sinclair scored in the 81st minute as former Barcelona and Real Madrid star Laudrup made a dream start.
Championship winners Reading rescued a 1-1 draw against Stoke at the Madejski Stadium on their return to the Premier League after a four-year absence.
Debutant Michael Kightly put Stoke ahead in the 34th minute thanks to a howler from Reading's Australian goalkeeper Adam Federici.
But Adam Le Fondre earned a point with a penalty in the 90th minute after Stoke midfielder Dean Whitehead was sent off.
At Craven Cottage, Fulham striker Mladen Petric showed there is life without Clint Dempsey as his debut double clinched a 5-0 win over Norwich.
With American forward Clint Dempsey reportedly on strike after his fall-out with the club over his desire to join Liverpool, Damien Duff set the ball rolling with the first goal in the 26th minute.
Petric, signed from Hamburg, increased the Cottagers' lead four minutes before half-time and he netted again with a deflected 54th minute strike.
Alex Kacaniklic struck in the 66th minute and Steve Sidwell's 87th minute penalty completed the rout.
Tottenham travel to Newcastle later on Saturday, while on Sunday champions Manchester City host Southampton and Champions League winners Chelsea face Wigan at the DW Stadium. On Monday, Everton entertain Manchester United.