The Reds came from a goal down to see off the Magpies at Anfield through Sadio Mane’s first-half double and a sumptuous strike by Mohamed Salah after the interval.
Watch: Liverpool 3-1 Newcastle in 90 seconds
The clash marked the beginning of a seven-game run in three competitions until the next international break in early October.
With the start of Liverpool’s Champions League campaign to come as soon as Tuesday night, Robertson explained why recovery and determination is imperative.
“August was relaxed in terms of what we’re used to but September is back to the busy schedule,” the Scot told Liverpoolfc.com. “The Champions League starts on Tuesday and we’ll be on a flight on Monday.
“So it’s all about recovering, we need to recover properly and we need to be ready to go on Tuesday. September is a busy period – we need to come through it firing and get the results we need.”
The Reds fell behind in a Premier League match for the first time since early April when Jetro Willems unleased a blast past Adrian in the seventh minute.
Jürgen Klopp’s men needed time to find their stride as they plotted a comeback, which began when Mane swept home an excellent curler at the Kop end.
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Robertson, who previously played under Newcastle boss Steve Bruce at Hull City, knew it was crucial Liverpool found an equaliser sooner rather than later.
“Here, we’ve not been behind very often so it was a good reaction because sometimes when it doesn’t happen very often, people can be a bit stunned by it – players and fans,” said the left-back.
“Everyone reacted really well and luckily we got back on level terms because the longer the game goes, Steve Bruce’s game plan comes in; I’ve been a part of it and I know how good they are at it. Luckily we got on level terms quite quickly.”
Though not on the scoresheet, Roberto Firmino shone after being introduced 10 minutes before half-time for the injured Divock Origi.
Firmino set up Mane to put the hosts ahead within moments of taking to the pitch and dazzled during a second period punctuated by his superb assist for Salah.
“We’re gutted for big Div coming off – hopefully it’s not too serious but he had to come off at that time,” said Robertson. “But to bring Bobby on is always a nice sub to have.
“Obviously he came back late from internationals and the manager decided to put him on the bench. When he came on he showed his class and could probably have had three or four assists.
“He had a big impact and that’s what we needed. Luckily we had enough for the three points.”