Alvaro Morata believes Chelsea's emphatic win against Stoke City on Saturday (23 September) sent a message to their Premier League rivals.
The former Real Madrid striker clinched his first hat-trick for the Blues as they won 4-0 at the bet365 Stadium to remain within two points of the two Manchester club, who are currently leading the Premier League table.
Since becoming Chelsea's record signing in the summer, Morata has hit the ground running, scoring six goals in six league appearances to help the defending champions put a wobbly start to the season behind them.
"We sent a message to the Premier League,"said the Spaniard.
"Chelsea is in the fight for the title."
Chelsea will hope Morata can transfer his Premier League form onto the Champions League stage when they travel to Madrid to face Atletico on Wednesday (27 September). As a former Real Madrid man, Morata is unlikely to be welcome at the Wanda Metropolitano but his teammate Thibaut Courtois has backed him to deal with the pressure.
"We already know he is a top striker, we know he has this ability and his hat-trick felt good for him and all the team," said the Chelsea goalkeeper.
"A striker lives off goals and he has already scored a few important ones, but I think he will get a different reception to me on Wednesday night. Alvaro played a lot of games against Atletico and it will be a big game against his old rivals."
Courtois spent three seasons on loan with Atletico between 2011 and 2014, winning the Europa League, the Spanish Cup and La Liga. However, the Belgium international admitted feelings will be left in the dressing room on Wednesday, as Chelsea look to continue their positive start to their Champions League campaign, after beating Qarabag 6-0 in their opening game.
"It will be more friendly for me, but for 90 minutes I will also be their rival," he explained.
"There are a lot of people close to my heart who still play there, some good friends. It will be special for me to go back, but this time I hope we win.
"We have started a difficult week well, and now we have two massive games before the international break."
Chelsea host top-of-the table Manchester City in the 5.30pm kick-off on Saturday (30 September), knowing that a win would see them overtake Pep Guardiola's side. City have won just two out of their last 10 Premier League games at Stamford Bridge and were beaten in both fixtures last season, but arrive in London with the league's best attacking record and joint-best defensive record.
"City are going really well and they score a lot goals, but we know their players and it is nothing new," said Courtois.
"Maybe their players are rolling even better this season, but we will be ready for them. If we want to close that gap, we need to try and win next week."
The game against Atletico will also see Chelsea and Diego Costa cross paths again, after the Spain international ended a long-running saga by returning to the Spanish capital last week in a £53m move.
Costa had made no secret of his desire to leave Chelsea during the transfer window and staunchly refused to return to the club's training complex in Cobham after being told he was no longer required by Antonio Conte.
However, the 28-year-old will not be able to play for his new side until January due to Atletico's player registration ban.