Robertson played 120 minutes before a nail-biting penalty shoot-out on Thursday night, as David Marshall stepped up to save Aleksander Mitrović's penalty to send Scotland to their first tournament since the 1998 World Cup in France.
Clarke's team squeezed past the Israelis last month to tee up their play-off final with Serbia - and the boss is expecting another test tonight as they teams meet for the fifth time in two years.
In contrast, a dejected Serbia trudged off into the tunnel, having missed an opportunity to reach their first European Championship finals as an independent nation.
It's hard to believe it's six days since Scotland ended 22 years of hurt and secured their place at Euro 2020 next summer.
Asia just created the world's largest trading bloc with 15 economies
This means that the free trade bloc would encompass almost one-third of the world's population and economic output. Notably absent from the signing was India, which withdrew from negotiations in November past year .
Scotland manager Steve Clarke was overjoyed to give the Scottish people something to cheer about during "a hard time for the nation" amid the Covid-19 pandemic, after they beat Serbia on Thursday to reach Euro 2020. This is a battling group with players and management that shows the grit needed to make a nation proud. It was the 10th penalty taken in the shootout. "We deserved the win and we are delighted for all the fans and our families who couldn't be here". That's a monkey off the back now, ' Christie said.
"We didn't get the result tonight [v Slovakia], but I still think everyone gave as much as they could in that performance".
The Israelis also have plenty to play for as they look for the win that would save them from relegation to the lower tier of the Nations League next time out. The Motherwell pair of Stephen O'Donnell and Declan Gallagher came to Clarke's attention when he was in charge at Kilmarnock and Gallagher's confident handling of Mitrovic on Thursday endorsed the manager's eye for innate talent and character.
"We want to be a squad that can achieve back-to-back major tournaments and more success".
"We know it, you know it, everyone knows it and it's a monkey off the back now".