Jota and Robertson became close friends during their time at Liverpool before the former's spell there was cruelly cut short when he died, aged 28, in a car crash last July.

Robertson, who ended a trophy-laden nine year spell with Liverpool when he signed for Tottenham Hotspur last Friday, had paid tribute to Jota after the Scots secured their place at the finals for the first time since 1998.

"We spoke so much about going to the World Cup because he missed the last one with Portugal and I did with Scotland," Robertson said last November after the play-off win over Denmark.

"I know he'll be smiling over me today."

Rute Cardoso, the mother of Jota's three children, said in her letter -- which FIFA published along with a video of Robertson reading it -- his words that night had touched her deeply.

"When I heard your words and learnt what you felt on that day when Scotland qualified for the World Cup, after so many years of waiting, I realised that Diogo never truly left the pitch," wrote Cardoso, who married Jota days before he died alongside his brother Andre Silva.

"By achieving that moment and securing your place at the World Cup, you won't be going alone.

- 'Full of emotion' -

"You'll be taking his dream with you too. And when you step on to the pitch, I know it won't just be you walking out. Diogo will be with you in your thoughts, in your steps, in your heart.

"So today, I want to thank you. Thank you for not forgetting him.

"Thank you for taking him with you. Thank you for turning the pain of loss into strength and into something so beautiful.

"That's how we do it here at home too. Every day. He would be, and is, incredibly proud of you.

"Cherish that dream, Andy. Live it for yourself and for him."

Robertson said Cardoso's letter would stay with him for a "very long time".

"I'll carry him in my heart and I know he'll be with me come the first game, come the second game, come the third game and hopefully beyond that," said Robertson.

"He's always there. The memories are always something that we bring up and sometimes laugh, sometimes cry.

"And that will be no different, especially going into a tournament which is full of emotion. I know he'll be right at the front of my mind.

"I'm not only just playing for me. I'm playing for both of us."

Robertson will hope to honour the memory of Jota by becoming the first Scotland skipper to lead the side into the knock-out stages of the finals at the ninth attempt.

The Scots open their campaign against Haiti on June 13 in Boston, followed by tougher dates with African champions Morocco, also in Boston on June 19, and five-time winners Brazil on June 24 in Miami.

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