The 42-year-old topped a string of gruelling fundraising challenges with seven ultramarathons in seven days in September, all in honour of former Leeds team-mate Burrow, who is living with motor neurone disease.
Sinfield explained how Burrow’s inspirational handling of MND changed his own life, forcing him to seek the new challenge of coaching to fill the void left by his playing retirement.
Less than 18 months after joining Leicester, Sinfield now finds himself in a pivotal position in England’s new Test set-up – and he was quick to credit Burrow’s influence on his meteoric coaching rise.
“My old mate got diagnosed with motor neurone disease, as you all know, back in December 2019,” said Sinfield. “And that next 12 months a whole lot happened in the UK with Covid and where we went as a society and a community.
“And towards the back end of that year I was able to do the first challenge and as soon as I finished that challenge I knew I had to do something different with my life. A lot of that is based around Rob.
“Rob's faced with this horrific disease and I realised I needed to take some risk and I needed to find more challenge in my life. So very quickly, I knew I needed to go and do something else. The opportunity at Leicester presented itself, which I jumped at. I didn't have any idea at that stage I'd find myself here in 15, 16 months time.
“If you'd have told me, I'd have to pinch myself. It's been an unbelievable journey, working alongside Steve and the staff at Leicester. I've loved every single minute of it.
“A couple of things I've got from Rob about fight; people I have been able to surround myself with over the last couple of years have been real fighters and they also care about the people around them.
“Rob's inspired me in so many different ways and it's probably a large reason why I'm here today because without that horrible news I'm not quite sure I would have come down this path.”
Sinfield admitted when he retired fully from rugby in 2018 that he never envisaged moving into coaching. But Burrow’s circumstances have had a profound effect on England’s new no2, with Sinfield quickly realising he needed fresh challenges.
The first few days at Leicester proved a major culture shock, but once Sinfield warmed to Welford Road, he and Borthwick delivered the 2022 Premiership title.
The RFU sacked Eddie Jones in December after England slipped to their worst run of calendar-year results since 2008. Now Borthwick and Sinfield are busy launching a new era, and with just nine Test matches to go before the autumn’s World Cup.
“With what happened to Rob, I just felt I needed to take some risk, and take on a challenge that, I have to admit, after the first couple of days, I thought to myself, ‘what have I done? Can I survive?’” said Sinfield.
“And then very quickly, with that support and care from Steve, the coaching team, players, very quickly, started to get fulfilment from it, and really enjoyed it.
“And now I bring Steve in here. He's a guy who's had a huge influence on me in the last 15 months, probably a little bit longer than that since we started to have very brief chats about me joining Leicester.
“Steve has got those two qualities that I've just mentioned. You know he's a fighter, you know how hard he works, you know he's obsessed with winning, you know how diligent he is.
“The bit you probably don't see is how much he cares. During my last challenge, which was seven ultras, I got a text off five people every single night. My wife, my two boys, Rob Burrow and Steve.
“Steve was right behind everything we were trying to do and people don't hear that or see that. But he cares as much as anybody I've been around.
“To be here in such a short space of time, I've worked really hard. I have got a lot of holes in my knowledge and probably still a part of me has to translate things across. But I don't hide that fact.
“I'm happy to share it with the players. I don’t mind being wrong but if I'm wrong, I will work as hard as I can to make sure I'm not again.”