Arsenal and Chelsea could struggle to mount Premier League title bids this season unless they strengthen their respective squads before the end of the transfer window, according to former England striker Alan Shearer.

Chelsea stormed to the title last season and later signed Alvaro Morata in a club-record £70m (€77.3m, $91.3m) deal. Defender Antonio Rudiger also joined from AS Roma for £31.5m and Tiemoue Bakayoko arrived from AS Monaco for £36m.

However, Antonio Conte has demanded more arrivals, particularly after the club allowed Nemanja Matic to join Manchester United last week. Diego Costa is also expected to leave Stamford Bridge before the end of the month.

The Italian's patience appears to be wearing thin and the Blues are reportedly targeting Leicester City midfielder Danny Drinkwater and Southampton captain Virgil van Dijk, who has submitted a transfer request as he seeks to force his way out of St Mary's.

Conte's frustration is perfectly understandable according to Shearer, who believes the defending champions do not have the squad depth required to be competitive on multiple fronts.

"Chelsea have 13 or 14 very good players who will match anyone," the Premier League's record goalscorer wrote in his column for The Sun. "But with Champions League football this season, they are going to need more if they want to compete on all fronts.

"They would need a lot of luck with injuries to get through the campaign and be successful with the squad they have at the moment. I think they still need at least two or three new additions between now and the end of the transfer window."

The former Southampton, Blackburn Rovers and Newcastle United striker was not overly optimistic about Arsenal's chances either, despite the fact they beat Chelsea on penalties in the Community Shield on Sunday (6 August).

Earlier this summer, the Gunners broke their own transfer record by signing Alexandre Lacazette from Lyon in a £52.6m deal, while defender Sead Kolasinac, who scored on his debut at the weekend, joined on a free transfer from Schalke.

While Arsene Wenger seems to have convinced Alexis Sanchez to remain at the Emirates Stadium for another season, Shearer warns the lack of signings could come back to haunt the Frenchman.

"Lacazette and Sead Kolasinac, are their only two signings this summer," he wrote. "That is not enough for the Gunners if they want to be challenging for the title, which is ultimately what their supporters want.

"It is also going to be interesting to see how the situation regarding Alexis Sanchez plays out. Arsene is adamant that his star man is staying. But if you are the Arsenal board, and you see that a player worth more than £50m could leave for nothing next summer, that must be very hard to take."

Antonio Conte
Conte is not content with his Chelsea squad Getty Images