John Terry has warned his Chelsea team-mates against complacency born of their five-point lead at the top of the Premier League and urged the team to maintain their focus and form once the topflight campaign resumes after the international break.

The impressive nature of their derby victory over Arsenal on Sunday had prompted the visiting goalkeeper, Wojciech Szczesny, to acknowledge “the brilliance” mustered by the leaders in securing the 2-0 success at Stamford Bridge to restore that eye-catching advantage at the summit. Chelsea are the only unbeaten team in the division having dropped just two points, at the champions Manchester City, though the captain is wary of the threat still posed by the pack when they resume their challenge at Crystal Palace later this month.

“Clearly it’s not over,” Terry said. “Other teams have been in that position before. It’s nice to have the lead, but when you’re at the top everyone wants to shoot you down, from top to bottom. That’s the good thing about the Premier League and why everyone loves it. Teams are out to get us because we are at the top and playing well at the moment. The international break has come and we need to come back and maintain our form after that as well. It’s very important we do that.

“It’s obviously better to be leading than being behind. But when you’re behind – and we’ve been there – you have something to fight for, something to chase. When you’re at the top and have a five-point cushion, you’re just hoping a couple of the teams behind you slip up again and that increases it to eight or nine. If that happens it’s a lot of points to give up early on. All we can do is keep winning and wait for those teams to slip up.”

Chelsea’s campaign has been driven by the impact made by their two major summer signings, Cesc Fàbregas and Diego Costa, who have made a staggering impact since arriving from Barcelona and Atlético Madrid respectively. Both have joined up with the Spain squad before their Euro 2016 qualifiers against Slovakia and Luxembourg, with Terry apparently unconcerned by the state of the nine-goal forward’s hamstring, an injury which has been giving José Mourinho sleepless nights in recent weeks.

“I’m not sure where that’s coming from,” Terry said when asked about the thigh complaint that has hampered Costa since he aggravated the injury in his country’s friendly defeat to France last month. “He certainly isn’t showing that against me in training. He is training every day, he looks sharp, he looks angry, he looks aggressive. He’s fit at the moment and that’s the main thing. It’s been so important that the new guys have hit the ground running. Cesc knew the league, but for Diego to come in and score the goals he has and be the handful that he is … he’s been a nightmare for defenders.”

Costa’s goal – his ninth in seven league games – had killed off Arsenal’s challenge on Sunday with a first league loss this season something of a reality check for the visitors, despite an improved performance on the 6-0 drubbing to the same opponents back in March. Szczesny said: “It was an even game, but Chelsea have an ability to keep clean sheets at home and I thought they were very good, they took their chances with two brilliant moments. One, a brilliant run from Hazard which led to the penalty. On the second goal, the ball from Cesc and the finish … Sometimes you’ve got to take your hat off to the brilliance of the opposition. You can’t say we’ve played badly. It’s just that we came up against a very strong side, probably the favourites to win the Premier League at this point.”

“Last year it was a freak result at Stamford Bridge,” Jack Wilshere said. “No team, not even a team in the bottom half, should be losing 6-0. But this year, in the big games we really feel we’re closer. Last year, in the big matches, the game was almost over after 20 minutes. We were 1-0 down, or two down, and when you go behind at places like Chelsea it’s really tough. This year we were really focused, we kept it tight and you can’t really plan for a bit of a magic from Eden Hazard. Up until then we’d defended well and even created a few opportunities ourselves, so we feel like we are getting better as a defensive unit.”

The same might apply to Chelsea, whose early season sloppiness at the back – masked by the number of goals they were plundering at the other end – has been eradicated and the defence having since mustered three successive clean sheets. Arsenal did not manage a shot on target all afternoon. “Everyone was questioning the defence early on in the season, but it’s going to happen,” Terry said. “There are so many good teams and individuals in the league, we are going to concede goals. The important thing is we have goals in us. We have had a few clean sheets on the bounce, defensively we have been doing very well, not just the back four, but it’s also people like Eden, André [Schürrle] coming back and able to go forward as well. That’s the key. We are more attacking this year, but defensively we are now very solid.”