Losing a set and 4-0 lead to Serena Williams at a Grand Slam tournament, which Victoria Azarenka did at the 2010 Australian Open, is one thing. Losing that same lead to Mona Barthel in the second round at Indian Wells is another. The top seed seemed to realize that distinction just in time on Friday, recovering from a double-break deficit in the third set, among other perilous moments, to survive Barthel, 6-4, 6-7 (4), 7-6 (6).

When I saw Novak Djokovic in person for the first time last year, in Montreal, he gave off the aura of a world No. 1. I was curious to see if Azarenka, who’s occupied the top spot for just over a month, would do the same today. She certainly looked the part, wearing the same attire as she had for the first 17 matches of 2012, all wins. And for a while, she played the part, too. Azarenka made Barthel pay for any short ball, returned aggressively, and generally played points long enough to either put herself in a winning position or force an error from her opponent.

But one thing Azarenka never had working today was her serve. Barthel also returned aggressively, not necessarily by choice, but because she could—Azarenka didn’t dictate play when holding the balls. Double faults were plentiful; she had 12 in all.

But a so-so serve doesn’t matter much when you’re leading by a set and two breaks. However, it was at this juncture that the silent Barthel produced some deadly tennis. The German flattened out her strokes, pushing Azarenka back and into retrieval mode. This occured in both players’ service games, sending the already vocal Azarenka into several screaming fits. Before you knew it, Azarenka’s lead was just 5-4, and when she failed to convert a match point, Barthel took full advantage, winning an eventual tiebreaker. For Vika, it was opportunity for an easy night lost. For Mona, it was a work of art.

A new set did nothing to change the momentum of the match. Barthel’s blitzkrieg continued, which included a number of down-the-line winners that elicited huge cheers from the growing, curious crowd. Azarenka’s frustration mounted, punctuated when she double-faulted on three consecutive points to fall behind 4-1.

Still, if the world No. 1 can blow a double-break lead and lose a set, so can the world No. 37. And that’s exactly what happened, more because of Barthel’s nerves than anything. Her once fearsome groundstrokes vanished, along with her follow-through. She was unlucky, too—up a Hawk-Eye review confirmed that Azarenka saved a break point by an angstrom; it would have given Barthel an even greater cushion. Ultimately, that may have cost her the match. Tight as a drum, Barthel failed to serve it out at 5-4, and suddenly she knew how Azarenka felt a set earlier.

At that point, I felt confident that Azarenka couldn’t possibly lose. My conviction was tested when Barthel again had a chance to serve out the match at 6-5, and when Azarenka’s 3-0 lead in the third-set tiebreaker became 4-4. But three hours after it began, Azarenka’s winning streak improved to 18 matches. What did we learn from this? I’ll let Steve Tignor try his hand on that in a forthcoming post. But I can say this for sure: Not all wins are created equal.

—Ed McGrogan