Veteran Blues striker Andrew Abba provided the second equaliser in the 71st minute before last season's golden boot striker, Martin Bueno, clinched the winner in the 88th minute.
"They got themselves organised so I'd say they've done a little bit of work on that," he said. "They dropped off very deep to make things as difficult for us as they could with 11 players behind the ball at all times and then they counter-attacked when they could so they were pretty difficult to break down."
Robertson again reiterated the Rovers created numerous chances but weren't clinical enough in planting the ball into the net.
"You know, fair play to them because they made it really hard for us and we've had to earn our three points today."
Unbeaten Western Suburbs drew 3-all with North Wellington to lose their top perch on the ladder on Good Friday, a result Waterside Karori registered against Wellington United while Lower Hutt pipped Stop Out 2-1.
However, Suburbs, who face the Rovers in a 2pm kick at Bluewater Stadium this Sunday, also drew against Karori today to sit four points adrift of the Blues.
With five wins from as many outings, the Fergus Neil-captained visitors are undefeated in 13 games, with 20 victories from their last 23 games dating back to last season when they drew a match and lost two.
Robertson said another late victory today is a comforting endorsement of his players' fitness levels where they had been dominating games for long spells to keep topping up the confidence tank.
"We scored three goals away from home again," he said.