Chelsea goalkeeper Thibaut Courtois believes the Blues are struggling to replicate their perfect start to the campaign because of the defensive approach from their rivals.
Manager Jose Mourinho's side made an extraordinary start to the campaign, winning their first 10 Premier League games at Stamford Bridge while securing the qualification to the Champions League last-16 as leaders of their group.
But the Blues have dropped points in three of their four last home Premier League games – against Manchester City, Burnley and Southampton – and were also knocked out on away goals from the European competition by Paris Saint-Germain after a disappointed 2-2 draw.
Speaking after the 1-1 draw against Southampton on 15 March, Courtois explained: "Sometimes there are moments in a season where things aren't going as well as you want them to. Teams are playing very defensively against us; maybe at the start of the season they were more offensive and there was more space."
Diego Costa gave the lead to the Blues earlier in the game but Southampton quickly reacted to secure a draw from the penalty spot. "It's a pity we couldn't score the second goal; we pushed Southampton back into their box but we couldn't find the gaps to score," Courtois said. 'We had quite a few chances but Forster made some good saves."
Nevertheless, the Belgium international has hailed the importance of the point as, following Manchester City's defeat to Burnley, they are six points clear of Manuel Pellegrini's second-placed side with a game in hand.
Courtois said: "We've gained a point on Man City. Obviously if we were three ahead it would have been better so that's a pity, but Southampton are a good side, they've done well this season and it wasn't an easy game."