Because he "missed an absolute sitter," Robertson joked, there was no point in examining whether he had taken performance-enhancing drugs.
In an excerpt from his new book "Robbo: Now You're Gonna Believe Us" published on the Liverpool Echo, Robertson spoke about the disappointment of his side's last-16 elimination in March, which was the last game played with fans at Anfield before the coronavirus put a halt to football around the globe.
"Drained, defeated and disappointed, the last thing I wanted was to be picked for a drugs test," Robertson writes. "Atletico Madrid had just won at Anfield and our reign as European champions was over. All I wanted to do was get home to start dealing with our loss.
"No such luck. Doc Andy Massey tapped me on the shoulder and told me I’d been randomly selected along with Adrian. Seeing as I’d missed an absolute sitter and Adrian had made a costly error, I didn’t see much point in checking if either of us had taken anything that would enhance our performance.
"After Atletico there was one moment that I kept going over in my mind, wishing I could go back and make it right. I knew the chance that fell my way in the second half was one of the best we had during normal time.
"After Mo[hamed Salah]’s shot was deflected, the ball spun into an area that I could attack in front of the Kop goal and it felt like everything had aligned in my favour. It was my birthday, I’d never scored at the Kop end before and I knew if I made a good connection there would be nothing that even Jan Oblak, who was brilliant on the night, could do about it. It had to hit the back of the net. It just had to.
"Smash. It hit the bar. In fairness, Kieran Trippier leaned into me just as I made contact and that didn’t help but that was the moment I replayed in my head constantly for the next 24 hours. I blamed myself, no-one else."
Robertson aso spoke about the eerie aura of the game, which took place as the pandemic in Europe was worsening. Many, including the mayor of Liverpool, believe the match should not have gone forward, especially given that 3,000 fans travelled to Liverpool from Madrid.
"From what I had seen before and after we played Atletico and the stuff I had been seeing in the news, I just knew. I live in a country that hasn’t experienced a pandemic or had war visited upon it in my lifetime but all of a sudden everyone was facing up to a future in which the only real certainty was that people would die.
"All of our lives were about to change. I had seen that process start with my own eyes and in my own domain. Jurgen [Klopp]’s behaviour changing. A drugs test without an opposition player in the same room. No mascots. No handshakes before the game. All small differences but each symbolic in their own way and together adding up to something much bigger.
"This was only the start too and as much as I try to keep myself informed nothing could have prepared me for what was to follow."