Roger Federer pays touching tribute to COVID-19 nurse on Mother's Day

Roger Federer has brought smiles to countless people around the world with his effortless groundstrokes and silky movement on the court. But even off the court the Swiss maestro has the power to light up anyone's day, as Christianne Calderon found out.

Calderon, a frontline critical care nurse helping in the fight against the coronavirus pandemic at New York's Presbyterian Hospital was left overjoyed as the 20-time Grand Slam champion made a surprise appearance in an ESPN video interview.

Roger Federer is a master at spreading happiness

These are really great. Here is @rogerfederer and Eli Manning surprising Christianne Calderone, a nurse practioner in NYC. https://t.co/fE0lVF8PBX

— Richard Deitsch (@richarddeitsch) May 10, 2020

New York is the worst hit city in the USA, accounting for over 183,000 cases out of the 1.3 million reported in the country so far. The healthcare workers there are especially vulnerable to the deadly virus, but they have been putting duty first to save precious lives.

The ESPN video paid gratitude to the doctors, nurses, healthcare professionals, caregivers and all those selfless workers who are risking their own lives for the safety of others. In the video, presenter Tom Rinaldi conversed with Calderon, who shared the harrowing experience of working with infected patients.

The video showed how challenging a time it has been for the frontline workers, especially considering that the city has witnessed more than 21,000 deaths. It also revealed that Calderon, a mother of two, is an avid tennis fan and player who draws courage and confidence from her experiences on the court.

"I don't want to lose. And in the patient setting during this pandemic, winning is discharging the patient out of the ICU," said Calderon.

"That is winning. Or taking the tube out of the ventilator. That's winning. And because I always want to win, I celebrate every little minute changes, that are positive changes, I call it a win," she described.

But as the braveheart spoke in detail about her experiences, she had no idea of what was coming next. To her complete surprise, Roger Federer made a brief appearance, which left the nurse "shaking" in complete disbelief.

Watch as Roger Federer makes his appearance at 2:55

"People think, we the athletes, are superheroes. But we think the same about somebody like you Christianne. You are the hero because you actually do save lives. You actually do make that difference," said Federer in a heartfelt tribute.

The stupefied Calderon thanked the former World No. 1 and told him how much she admired his humility, before the tennis icon bid goodbye.

The ever-popular Roger Federer has won the ATP Fans' Favorite Award for 17 consecutive years

Roger Federer was not the only superstar athlete to make Calderon's day. While she was explaining why she didn't like to call herself a hero, former New York Giants quarterback Eli Manning also popped up to praise the medical personnel, leaving Calderon thrilled to bits.

"I'd like to be amongst the first to wish you a Happy Mother's Day. And also just sincere thank you for being on the frontline, for your work, your commitment, your selflessness and I think those three words describe what a hero is," said Manning.