Novak Djokovic wants Nemanja Vidic in his corner again at Wimbledon tomorrow after the Manchester United captain inspired the top seed to victory against Tomas Berdych yesterday.
Djokovic beat seventh seed Berdych 7-6 (7/5) 6-4 6-3 to move into his 13th consecutive grand slam semi-final.
Watching among the bumper crowd was Djokovic's fellow Serbian Vidic, who had left his seat vacant in the Royal Box on Centre Court to watch his countryman play on Court One.
Having come through his toughest test of Wimbledon, Djokovic will beckon Vidic back to south-west London for his semi-final against Juan Martin del Potro.
"He's a lucky charm. I'll make sure he's there (for the semi-final)," the 2011 champion said.
"We wanted to invite Nemanja because he's one of the most successful and most recognised Serbian people in the world.
"He accepted that, and he said he would be here in these days.
"I was very much delighted to see him in our box today and watching the match and supporting me.
"It's the first time he actually came to watch me. I've watched him before in the national team a few times. We met briefly.
"He plays for one of the best teams in the world. I was just very happy to see him there in the stands and supporting me."
Djokovic looked in serious danger of losing his first set of the tournament when Berdych gave as good as he got, the pair engaging in some captivating rallies from the baseline.
It only went Djokovic's way when he edged a nervous tie-break, and the world number one then lost two service games in a row to go 3-0 down in the second set. He eventually summoned the mental strength to break back and go on to record victory after two hours and 35 minutes on court.
Djokovic admitted he could have lost the match had he not stepped up his game in the second set.
"It was a very close match, it could have gone either way," Djokovic said.
"He could have won the first two sets, he had a double break in the second.
"I don't know how I managed to go ahead, I don't know how I turned it around. I am really happy with the performance. I am playing some of the best tennis on grass of my career.
"Tomas is a very powerful player. As you could see, we went toe to toe in the first set. It was a huge confidence boost to come back and go two sets up."
Djokovic has won eight of the 11 matches he has played against Del Potro, but the 2009 US Open champion has come out on top in their only meeting on grass, which came in the Olympic bronze medal match last summer.
The Argentinian eighth seed suffered a nasty fall in the opening game of his win over David Ferrer yesterday, but, ever the professional, Djokovic is not taking anything for granted.
"He is a great player. I have a great respect for him," the six-time major winner said of Del Potro.
"He's a grand slam winner. He has struggled with injuries in the last few years, but every time he comes back he comes back very strong because he just has this talent and quality.
Meanwhile, Juan Martin del Potro admits he will have to give up his Wimbledon dream if doctors tell him his battered body has taken enough punishment.
The combination of heavy strapping on his left knee and anti-inflammatories – "magic pills", Del Potro called them – saw the Argentinian through a remarkably one-sided Centre Court quarter-final against world number four David Ferrer.
After falling and ricking the knee in the final stages of his third-round win over Slovenian Grega Zemlja, eighth seed Del Potro went over in an almost identical fashion yesterday, inside the first game, as he chased down a ball to his left.
Somehow Del Potro recovered to pull off a 6-2 6-4 7-6 (7/5) victory, unleashing a barrage of just about the fiercest forehands ever witnessed at Wimbledon. But he admitted he was "really close" to having to pull out of the match.
And while he would love to add a second grand slam title to his 2009 US Open triumph, the 24-year-old said: "I'm not going to put my body at risk. The doctors tell me that with this tape and some anti-inflammatories I can play. If they say something different, I will think.
"I think I was close to retiring. But to be honest, I didn't want to retire in my first quarter at Wimbledon against David Ferrer. The doctors gave me good anti-inflammatories.
"I was thinking good things, being positive all the time. I never thought about my knee after the first set."
Novak Djokovic, the world number one, title favourite and former champion, represents the high wall that stands between Del Potro and the final. And even if the knee does begin to affect him in the semi-final against Djokovic, Del Potro is certain his opponent will also be feeling the strain of two weeks on grass.
He added: "I have experience with injuries. I know it's the semi-finals of a grand slam. All the players feel something, some pains. It's normal. I have my knee problem, but my opponent could have different injuries. You have to be stronger than the rest."