Southampton spent their pre-season camp in Germany, recording victories over Eintracht Braunschweig and Preussen Munster.
They begin their Carabao Cup campaign away to League Two side Colchester United on Saturday, then travel to Watford the following weekend for their league opener.
Over three seasons at St Mary’s, Downes has made more than 100 appearances, scoring six times and supplying four assists.
As he heads into his fourth year with the club, the midfielder says he’s in the best condition of his career.
Downes said the whole squad feels ready to get started.
He added that he feels better than ever, praised the manager’s influence, and believes his game intelligence and physical levels continue to improve as he looks ahead to the season.
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