Graeme Souness believes Chelsea will need to add further quality this summer if they want to successfully defend their Premier League title.

The Blues seemingly cruised to the title this term but former Liverpool star Souness feels Jose Mourinho has to attract top players to Stamford Bridge to keep their English rivals at bay.

"When you are at that level or perhaps any level, if you're not adding to it then you're standing still because your rivals will be strengthening," Souness said on Sky Sports.

"Manchester City will, Manchester United will and Arsenal certainly will. So Chelsea have to strengthen otherwise they're standing still."