The 35-year-old suffered from chronic sinusitis when he returned to Australia for the summer and it cost him about three weeks of training before the 2018 WorldTour opener.
The complaint was an unnecessary stress for the Dimension Data lead-out specialist, who is keen to change his fortune in what is a contract year for him and famed teammate Mark Cavendish.
"It was touch and go whether I'd make it here or not but in the last month it improved quite a bit. [I'm] probably just good enough to get through Down Under," he said in Adelaide.
Renshaw fractured his ankle at Scheldeprijs in April and then raced against time, training to the point of being "borderline crook", to compete in the Tour de France.
Cavendish there crashed out in stage four and Renshaw, in another dramatic twist, was ousted five days later after missing the time cut.
"I'm motivated to have a good year because last year was a shocker," he said.
"Last year with illnesses and crashes, we never really got rolling but now everything seems to be going good. We've got a few new riders in the team, which have improved the overall level a little bit so we should be better."
Renshaw's job won't change this season during which he is again set to pilot Cavendish, who also faced a series of illness and injury related setbacks in 2017.
The Australian has played a part in 22 of Cavendish's 30 Tour de France stage victories and appears set to stick with the Manxman as a package deal moving forward, just maybe not again over a three-year contract term.
"I'm sure once we catch-up we'll have a chat and then see where it goes," Renshaw said.
"I know my job and I know my role. It's experience that I bring and obviously the lead-out capabilities. I'd like to have it [the contract] sorted mid-year, just to know what I'm doing next year.
"I won't be signing a three-year deal, just year-by-year for the moment and see how it goes."
In the interim, the Cadel Evans Great Ocean Road Race, Dubai Tour and Abu Dhabi Tour, as well as Tirreno-Adriatico, Milan-San Remo and the Tour of California are all on a race schedule of redemption for Renshaw.
"[I'm] probably not getting faster but still have the strength and, for me, it's all about positioning in the final, rather than doing the maximum power every time," he said.