Arsenal began their Premier League title challenge by beating Nottingham Forest 2-1 on Saturday as Alexander Isak scored twice in Newcastle's 5-1 thrashing of Aston Villa.
After finishing second to Manchester City last season, Arsenal have splashed over £200 million on new signings to try and claim their first title for 20 years.
Declan Rice, Kai Havertz and Jurrien Timber all made their debuts at the Emirates and Arsenal should have had a far more convincing scoreline to show for their performance.
Eddie Nketiah opened the scoring after some sublime skill by Gabriel Martinelli opened up the Forest defence.
Bukayo Saka then curled into the top corner from outside the area, but the Gunners were guilty of not killing the game off.
Forest had barely threatened until the introduction of Anthony Elanga and Taiwo Awoniyi.
Former Manchester United winger Elanga marked his debut with a fine run and cross for Awoniyi to score in his fifth consecutive Premier League game eight minutes from time.
"We were super dominant," said Arsenal boss Mikel Arteta. "There's no question that we deserved to win the game.
"We have to be more ruthless and more critical of ourselves to be more pushy and kill the games."
Victory ensured Arsenal did not lose any early ground on City, who began the defence of their title with a 3-0 win at Burnley on Friday.
NEWCASTLE DEBUTANTS SHINE
Newcastle finished fourth last season to qualify for the Champions League for the first time in 20 years and their rise under the control of the Saudi sovereign wealth fund shows no sign of stopping.
Italian international Sandro Tonali enjoyed a dream debut as he fired the Magpies into the lead after just six minutes.
Villa equalised almost immediately through one of their own new signings Moussa Diaby.
But Unai Emery's men, who also ended last season strongly to qualify for Europe, collapsed after Isak restored Newcastle's lead.
The Swedish striker calmly slotted home his second just before the hour mark.
Harvey Barnes then came off the bench to exemplify Newcastle's new-found strength in depth as the former Leicester winger teed up Callum Wilson to make it 4-1 and then rounded off the scoring himself in stoppage time to put Eddie Howe's men top of the table.
NO CAICEDO, NO PROBLEM
Brighton shrugged off the absence of Moises Caicedo to thrash newcomers Luton 4-1.
The Ecuadorian is set to become the most expensive player in Premier League history after a £110 million deal was agreed with Liverpool.
However, Caicedo reportedly still prefers a move to Chelsea, who have had a series of bids rejected by Brighton.
Luton were making their top-flight return after 31 years, having risen from the fifth tier of English football in the past 10 seasons.
But they were outclassed at the Amex as Solly March headed in Kaoru Mitoma's cross to open the scoring.
Joao Pedro opened his Brighton account from the penalty spot in the second-half before Carlton Morris reduced Luton's arrears from the spot at the other end.
But late goals from Simon Adingra and Evan Ferguson gave a fairer reflection of Brighton's dominance.
"Not one of the best games in my time, but we need much time to reach the same level, the same quality of play of last season," said Brighton manager Roberto De Zerbi.
"We won a very tough game. I'm really pleased."
Everton's need for a striker was laid bare as the Toffees wasted numerous chances in losing 1-0 at home to Fulham. Bobby Decordova-Reid scored the only goal at Goodison Park 17 minutes from time.
Crystal Palace were also 1-0 victors at promoted Sheffield United thanks to Odsonne Edouard's second-half strike.
West Ham began life without Rice with a 1-1 draw at Bournemouth as Dominic Solanke's equaliser for the home side cancelled out Jarrod Bowen's opener.
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