Chelsea is one of the teams with best start in Europe. They have 5 wins and 2 draws in the Premier League and 2 narrow wins in the Champions League. Also, they beat Liverpool in the League Cup, so the Sarri effect is very positive. The Italian is an amazing coach, he did great things with Napoli, but couldn't win a title against Juve because the difference in quality remained big enough and because Juve has Allegri. With Chelsea, he has better team and a player like Hazard, one of the World's best players. Liverpool and Man.City play each against other later today, so Chelsea has a chance to climb up. This is going to be a season without mistakes, every lost points may be crucial. Chelsea played in the midweek against Hungarian MOL Vidi, but Sarri used 8-9 bench players to rest his best 11 for Southampton. There are no injury concerns, so Chelsea are ready for this match.
Southampton have bad history against Chelsea, having lost the last 6 matches. Last season, they wasted 2:0 and lost 2:3. Southampton also played in the midweek and won in the League Cup in Liverpool against Everton after penalties. I don't expect Southampton to have problems around possible relegation, but they are somehow weak in defense.
I expect Hazard, Willian and Kante to make the difference and bring Chelsea a precious win after 2 draws.