Arsenal defender Kieran Gibbs says Alexis Sanchez is like "an animal" in training and believes the forward's arrival has injected added belief into the Gunners squad.
Arsenal face Manchester City in the Community Shield at Wembley on Sunday, looking to lay down an early marker ahead of their Barclays Premier League opener against Crystal Palace.
The Gunners parted with around £35million to bring Sanchez to the Emirates this summer, a year after spending £42.4m on Mesut Ozil.
"It's great for the confidence of the squad. When players like Ozil and Sanchez come in it makes everyone feel good," Gibbs said.
"Mesut didn't come in with an arrogance about him - he came in like he still had something to prove, like he wasn't already a world-class player.
"Alexis has that same mentality. He's like an animal in training and on the pitch. He's everywhere. He never stops running. That's what we need.
"We can't just sign a superstar and think we're going to win everything. It's about attitude as well."
Ozil enjoyed an excellent start to life at Arsenal last season but the 25-year-old's form fell away as the campaign progressed, with fatigue and injury gradually taking their toll.
Signings from abroad often take time to adapt to the intensity of the Premier League but Sanchez's physical style may mean he is better-suited.
"Alexis has got straight into us," Gibbs said.
"You always worry about some players coming in and adapting to the Premier League but, to be honest, I don't see him struggling.
"You can see it in him that he's a tough character. He's come in and he can be that 20-goal-a-season striker every team needs."
Conceding goals - rather than scoring them - has been the greater problem for Arsenal in recent seasons, with many questioning the defensive spine throughout the side.
The Gunners were more solid last term but heavy defeats to Chelsea, Liverpool and Manchester City mean there is still room for improvement.
"We've got an exciting team and a lot of players who can make a difference going forward, so we just need to be aware as well of the other side of the game," Gibbs said.
"We want to be careful as well. We want to be well-balanced. We want to be aware we've got responsibilities.
"We're not going to be an all-out attack team this season and we're working hard in training on all aspects of our game."
Arsenal return to Wembley on Sunday with fond memories after beating Hull to win the FA Cup in May.
The victory ended an agonising nine-year wait for a trophy and Gibbs hopes the triumph is just the start of things to come.
"The boys definitely needed it - everyone involved in the club needed it," Gibbs said.
"It was a nice feeling and we need to use it as a stepping stone now for the rest of this season.
"It's not something where we think we can take our foot off the gas now, it's made us put our foot down even more."
Gibbs added: "It was a special feeling and extra-special because it was so long coming.
"It does feel different now. The ceiling is higher, we just feel more responsible and more mature because we've gone through a lot to win and you realise what it takes."