Matteo Berrettini and Grigor Dimitrov both reached the semi-finals at the US Open, the last Grand Slam before the ongoing Australian Open.

For the Italian, it was a breakthrough performance that saw him reach the top 10 of ATP. For the Bulgarian it was welcome return after close to two years in the wilderness of indifferent results.

On Wednesday, both the eighth seed and the eighteenth seed were dumped out in the second round of the Australian Open after five-set battles. Tennys Sandgren beat Berretini 7-6 (7), 6-4, 4-6, 2-6, 7-5 while Dimitrov went down to Tommy Paul 6-4, 7-6(6), 3-6, 6-7(3), 7-6(10-3), in four hours and 19 minutes.

Sandgren, tennis fans will remember, is the American who had stunned Stan Wawrinka and Dominic Thiem on his way to the quarter-finals in 2018. Berretini, on the other hand, has never gone beyond the first round before this year in Melbourne.

But Paul is a 22-year-old from America who had never won a Grand Slam match before this Australian Open, and was a qualifier in Melbourne last year.

He was up against Dimitrov, who can be considered a veteran at this stage. In fact, the season-opening Major is his most successful of the four. In 2017, he had had reached the semi-final in 2018, going down in a close five setter to Rafael Nadal, in 2018 – as the third seed – he had reached the quarter-finals in 2018 with a sparkling win over Nick Kyrgios and had lost in the fourth round last year.

But when it mattered the most, Paul looked the more composed and experienced of the two players and won the match tiebreak. Six time in the five-setter, Dimitrov was as close as two points to a win, even serving for the match in the fifth set. But the very fact that he sprayed errors all over in the 10-point tiebreak and lost seven straight points tells the same old story: Dimitrov couldn’t close the match, mentally.

There was a time when he was even considered a title favourite, but his sharp decline since winning his biggest career title at the ATP Finals in 2017 saw him fall as low as world No 78. Yet, he managed to somehow climb back into the Top 20 in the final few months of 2019. After a string of first-round losses, he reached the semi-finals at US Open and Paris Masters.

When he beat Roger Federer at US Open, it appeared that the Bulgarian, once called ‘baby Fed’ for his immaculate style of play, had arrested his freefall and found his footing.

But his loss to Paul, in a match he was serving for in the fifth set and had better numbers in almost all parameters, could just be his career in a nutshell – the chances to be in the top, a balance of classic and clinical strokes, solid athleticism, good numbers, but not a lot to show for it except fluctuations.

Maybe Dimitrov isn’t failing at big moments or suffering from a crisis of confidence. Maybe this erratic display is actually what his tennis career is about. Not a roller coaster that goes down and up but a pendulum, swinging back and forth in the same place.

While no one can doubt his talent and his hard work is without question as well, the 28-year-old is just one of those players destined to be on the fringes of men’s tennis due to his inconsistency.

Pressure or just his style?

In his second-round collapse on Wednesday, Dimitrov started on the backfoot when he dropped the first two sets to the Grand Slam rookie. He was leading 4-0 in the second set tiebreak and got the early break in the third, yet he found himself scrambling to keep himself alive. He had to save three break points in the 9th game of the fourth set to stay in the match.

But the catch is, he did it all and was serving at 30-0 to win. And then the classic Dimitrov mental block appeared and he squandered the lead and the subsequent tiebreak. Here was a player who has very little experience of playing a five-setter and was struggling physically who dominated a match tiebreak thanks to a string of unforced errors at crucial moments from a former semi-finalist.

Was it pressure or just the way he plays?

With about a decade of being on the tour, Dimitrov is no stranger to close matches. The idea behind most of his shot selection was right, if only he could execute it. But execution of the right tennis strokes in do-or-die moments requires more than a racquet and the prodigious talent and experience.

It needs immense mental composure, fortitude and unshakeable focus, the ability to regroup after a mistake. The intangible aspects that the Bulgarian has often shown to be lacking. For years he has tried to overcome the pressure and mental block when playing against the big names.

But now that uncertainty has creeped into matches against lower-ranked players as well. In the past, he has tried working on this with Andre Agassi, a player very vocal about mental struggles, but seems unable to overcome this invisible barrier.

In the year he turns 29, maybe the writing on the wall is getting clearer: At his best, Dimitrov is capable of beating any player on any given day. But on days when he plays at his normal level, he could lose to anyone.