The Uruguay international watched from the stands as Dejan Lovren headed home Adam Lallana's second-half corner - defending Rodgers described as "criminal".
Suarez is now available for Wednesday's Capital One Cup tie at Manchester United, where he is certain to receive a hostile welcome, and on the basis of this performance his injection of energy and goal threat cannot have been more perfectly timed.
"I think that is the big positive from today [Saturday] is the fact he is back and is available from next week," said Rodgers.
"Sometimes players like him can make the difference so it is going to be great to have him back and a real boost to have him back from Wednesday onwards.
"I think he is in good condition. He has been playing games behind closed doors and doing a lot of specific work with the conditioning team.
"He is not going to be 100 per cent but he is a worker and a fighter and his condition is good.
"He just needs to get games to bring him up to speed."
Rodgers was unhappy with a lacklustre performance from his side, who began the day top of the table.
Steven Gerrard tested Artur Boruc with a first-half free-kick and Daniel Sturridge should have had a penalty when caught by Lovren but the Reds did not create nearly enough to trouble the visitors and a 12-match unbeaten run spanning two seasons came to an end.
"I can't underestimate how well the players have done," he added.
"This is our first defeat since March, funnily enough against Southampton.
"We've had two poor performances against them and it's cost us.
"We are very disappointed. We never got going from the off, it was a bit lethargic and technically we were short."
Rodgers put out a back four consisting of four central defenders but he justified the decision by claiming he had little option - although it provided little help when it came to the goal.
"Jose Enrique is one we have to keep an eye on his knee and if there is an overload on that it can put him out long term," he said.
"It was what we had available. Kolo (Toure) and Mamadou (Sakho) have played at full-back: you lose a bit of that offensive threat but I think they coped as well as they possibly could.
"We conceded possession poorly (for the goal) and then we ended up conceding the corner and to lose a goal like what with so many defensive-minded players was criminal really."
Southampton manager Mauricio Pochettino felt his side grew in stature after an indifferent first half.
"We are really pleased and satisfied with the performance of the team," he said.
"Especially in the second half we were much superior to them and were able to develop how we wanted to play.
"We fully believed from the start. The secret was not conceding.
"In the second half we came out correcting what we hadn't done in the first half, when we were hanging back too much defensively.
"We were faithful to the philosophy of how we wanted to develop our game and over 90 minutes we were superior to them and were able to capitalise on the chances we created.
"Boruc was outstanding today but the rest of the squad were outstanding. It is not easy to come here and win so to do that makes us really pleased.
"All the players need to be congratulated on a great performance."