The Spaniard was not to be denied a goal though and coolly lifted Hazard's pass over McCarthy in stoppage time following a prolonged period of possession to seal his side's sixth league victory of the season.
The defence was, however, necessary as Chelsea bagged a total of 10 corners in the first half, constantly pressing and constantly looking unsafe against an extremely passive Southampton.
31' GOAL! A great challenge by Ross Barkley is played forward to Eden Hazard who waits on the edge of the box and finds the net easily.
Given the superior form of Chelsea, the Blues entered the Premier League match as favourites and they duly delivered on the tag from the kickoff. Ross Barkley won the ball back in the final third before slotting the ball through to Hazard, who finished emphatically. "He is doing well and working hard on the training ground", said Hazard. "He will become a very important player, and for the England national team".
The 27-year-old Hazard has been earning lots of praise for the performances he has been showing in recent weeks, and most Chelsea FC fans would probably agree that the Belgian is back to his best.
Arsenal boss Emery hails players for Fulham thrashing: Everyone important
Asked about the playmaker's injury, Emery replied: 'Yesterday he came in with pain and he could not train or play today'. The game would 5-1 to the Gunners , with their ninth win in a row pushing them ahead of Tottenham and into the top four.
Barkley scored one and made one for Chelsea.
Manolo Gabbiadini has conceded that he would have taken a closer look at offers in the summer had he known he would continue to remain a bit part player at Southampton. The Belgium worldwide was a constant torment to Southampton's backline who had no real answer to his creativity, pace and world-class skill.
TALKING POINT - should Chelsea's second goal have stood?
Chelsea's efforts paid off in the 57th minute, with Barkley extending the Blues' lead as he tapped in from close range.
FW Pedro, NR - Replaced Willian but didn't bring any fresh ideas to Chelsea's attack.
Matteo Kovacic (5): he played a defensive game.