"When it was not all easy we again found the resources to win the game".
Hart produced a brilliant flying save to deny Marcos Alonso a winning goal.
Welbeck is expected to play a key role in the final stretch of the season after Mkhitaryan suffered a knee-ligament injury in the 4-1 win over CSKA Moscow in the first leg of their Europa League quarter-final last week.
While West Ham moved six points clear of the relegation zone, Chelsea fans vented their frustration after the latest in a series of poor results.
The Egypt global was sent off for the first time in his professional career in the 91st minute of this past weekend's Premier League win over the Saints after an altercation with Jack Stephens.
Shane Long gave the Saints the lead after 17 minutes, nipping in ahead of defender Shkodran Mustafi.
"People questioned whether he would come back and he continues to go".
There were chances at either end before Welbeck grabbed his first goal minutes before the break, only for Charlie Austin to rekindle the visitors' hopes after some brilliant work from Cedric.
"He had every reason to feel sorry for himself".
After failing to qualify for the Uefa Champions League for the first time in his 22-year reign, the Gunners are on the verge of missing out again as they are now 13 points adrift of the top four, with six English Premier League games left this season.