Novak Djokovic stormed onto the big stage of the professional tennis more than a decade ago. A runner-up of the 2007 US Open, that young tennis player from Serbia would become one of the greatest in the sport's history. At his peak, the Serb put in some flawless tennis dominating the men's circuit for years. In doing so, he managed to outlast both Federer and Nadal both on grass and clay.

But, it's been almost two years since Djokovic completed a career slam after winning that elusive French Open [VIDEO] title. From that point on, the vector went downward as he has never fully recovered. His last big run was toward the end of 2016 when he made it into another US Open final only to lose that to Stan Wawrinka.

It's no longer about an injured elbow

A twelve-time Grand Slam titlist, Novak Djokovic began to taste the bitterness that comes once an athlete realizes they're injury plagued. After a slow start of the 2017 season, Djokovic saw his game disintegrating due to a cumulus of variables. At first, it seemed more like a burnout symptom and a general lack of pace and rhythm. Later, we learned that an injury on his elbow was at the core of his lack of luster. Eventually, the Serb decided to call a premature end to the season after being forced to withdraw during his quarterfinal match at Wimbledon.

The long hiatus from the spotlight did little for his cause as Djokovic became even more fragile. We're deep into this season, and he holds a laughable collection of numbers. Currently ranked 12th in the world, he is 5-5 in competition, and we're already into the clay segment of the calendar.

In his latest appearance, the 30-year-old lost a three-set match to Martin Klizan, a former top 30 player currently ranked way outside the first hundred. Djokovic chose to compete in Barcelona as a result of his premature exit in Monte Carlo.

After yesterday's blunder, it's hard to predict how the rest of the clay season [VIDEO] will unfold for the former world No. 1.

Djokovic should start feeling the pressure soon

During the next few weeks, Djokovic should find a way to pull his act together. If he fails to gain some momentum, he will see his name descending into the meanders of the top 50 or worse.

Back in 2017, he was a runner-up in Rome, a Masters 1000 event while at the french open he made it only to the quarterfinals. These two events alone means roughly 1000 points Djokovic must find a way to defend.

With each tournament that goes by, Novak Djokovic's window of opportunity shrinks even more. He may even run out of time if the trend continues.