Mauricio Pochettino has told Chelsea’s players they need to be more naughty if they are to reach the level required to move on from an indifferent start to the season.

The team have dominated for long periods in all four Premier League games so far but defensive errors and a continued lack of penetration in attack have meant they have picked up just four points and sit 12th.

Defeat at home to Nottingham Forest before the international break was a microcosm of the side’s early struggles under Pochettino, with the visitors’ Anthony Elanga allowed to run freely through the heart of Chelsea’s defence to score the game’s only goal before striker Nicolas Jackson skied a gilt-edged chance to rescue a point.

It mirrored the loss to West Ham in August in which the team controlled the first half at the London Stadium before allowing their hosts to nick a 3-1 win, thanks in part to a missed penalty from Enzo Fernandez and a spot-kick conceded by record-signing Moises Caicedo on his debut.

The manager said that whilst performances warranted a greater points return, his players need to sharpen their competitive instincts if they are to make good on his stated aim of returning the club to the Champions League.

The team face Bournemouth at the Vitality Stadium on Sunday looking to win away from home for only the second time since March.

“The team performance was good in the first month,” said Pochettino. “We didn’t get the points that we deserved. The organisation was good, the way that want to play. Players believe in the way that we want to play.

“If you see the data, we are very good in possession, we are very good in construction and building. Only what we are missing is to score goals. That’s the most important thing in football.

“We want to be more competitive. We cannot concede this type of goal we conceded against Nottingham. We cannot be so weak, we need to be more solid. We have players with experience, players that can do better.

“At the moment I think my feeling is bad because we are playing well, we are showing to everyone we can compete, we dominate games against teams like Liverpool.

“But in the end we need to be more competitive – I say that because I don’t want to use another word. We need to be more naughty, more aggressive.

“They’re not too nice. (They need) to compete better. To increase our level is not about our quality, it’s to compete. To compete more in every single moment of the game that requires some thing to do. Because we’re still building the team, finding this balance, for sure it’s a matter of time.

“I try to describe why we didn’t get the points we deserved. At some moment of the game you need to show more this quality, this mental strength, to have this experience to manage better to deal with some circumstance in the game. Sometimes it’s not about only talent.

“When you see the Forest game after two weeks, the time we’ve spent trying to identify why we lost the game, it’s really tough. But that’s not to do with last season, we can’t blame last season. We need to blame ourselves and find solutions in ourselves. We cannot blame the past, we cannot blame the feeling of last season. Now it’s a new era, everything is new.

Pochettino confirmed that Romeo Lavia faces a spell out of the team after injuring his ankle in training, but could not say how long the summer signing from Southampton will be out.

However, an injury of this kind typically requires six weeks of recovery time, meaning the £58million Belgium international is unlikely to make his debut for the club before November.

“(We are) really disappointed because he was training really well last week,” said Pochettino. “He’s twisted his ankle and now we wait for Monday to hear from the doctor.

“We hope it’s not a big issue. It’s real shame. It’s a sad situation because he was nearly fit to be involved again with the team. We don’t know (time). We need to assess him.”

Neither Armando Broja nor Benoit Badiashile will be fit to feature against Bournemouth though both are back in full training and took part in internal matches during the international break.

Reece James, who went off injured during the season opener against Liverpool in August, is not fit to return but is back working with the ball in training.

“Reece is recovering well,” said Pochettino. “I can’t say if he’s close or not, because we assess him every single day. He’s started doing things on the pitch with the ball. He’s really well, he’s desperate to come again and help the team. I hope that he’s close and can be available before the next international break.”

The manager added that Trevoh Chalobah remains in his plans despite reports linking him with a move in January.

“Chalobah is in my plan. No one is going to decide for me. The message is that all the players who are going to be here in January or after January, I am going to be involved in the decision.”