One of London’s major landmarks may be an enormous ferris wheel, but U.S. fencer Mariel Zagunis has been on much more of a roller-coaster ride at these Olympics. Zagunis kicked off the Games in style, enjoying the honor of bearing the flag for the United States team in the opening ceremonies. But then she blew a huge lead in her semifinal matchup and ultimately missed out on a medal altogether, this after winning gold in both 2004 and 2008.

Zagunis didn’t take the latter development particularly well, at least not according to our own Mike Wise, but perhaps the former fencing champion can take grim solace in an apparent trend — flag-bearers for a number of countries have had disappointing showings so far. Here are just a few examples:

Agnieszka Radwanska, Poland: Wimbledon runner-up and No. 2 seed at the Games was upset in the first round by the world’s 24th-ranked player, Julia Goerges of Germany.

Stanislas Wawrinka, Switzerland: Was paired with Wimbledon champion Roger Federer, with whom Wawrinka won the Olympic doubles title in 2008, but the duo got ousted by Israel’s Jonathan Erlich and Andy Ram in the second round.

Lauren Jackson, Australia: Basketball star faces a harder-than-expected task in getting her team out of group play after it lost to unheralded France; she also received congratulations for setting the all-time scoring record in the Games before FIBA announced that it had neglected to notice that another player still had more points.

Luciana Aymar, Argentina: Like Jackson, Aymar still has a chance at ultimate success in London, but hockey player so revered in her home country she gets likened to Diego Maradona couldn’t prevent the underdog U.S. from repeating the huge upset it pulled against Argentina in October.

Marcos Baghdatis, Cyprus: Had the misfortune of being placed in the same bracket as local hero Andy Murray, then blew a one-set lead against Murray to miss out on a quarterfinals berth.

Peter Kauzer, Slovenia: 2009 and ’11 world champ in kayaking was widely seen as the favorite in London but didn’t even make the podium, finishing sixth in the K-1 event.

Telma Monteiro, Portugal: No. 2 seed in the women’s 57-kilogram judo competition fell to American Marti Malloy in the first round, this after defeating Malloy the previous two times they had fought.

Elnur Mammadli, Azerbaijan, and Srdjan Mrvaljevic, Montenegro: The 2008 Olympic titlist and 2011 world championship runner-up, respectively, both became footnotes in the Cinderella story of Antoine Valois-Fortier, who went on to an unexpected bronze medal for Canada.

Denisse van Lamoen, Chile: World champion archer dumped in the first round by the woman she defeated for the title last year, Georgia’s Kristine Esebua, in straight sets.

To be fair, many flag-bearers have done well — Bulgarian gymnast Lordan Lovtchev and Singapore’s Tianwei Feng (table tennis) come to mind.

And, of course, several flag-bearers, including such big names as Maria Sharapova, Novak Djokovic and Pau Gasol, are still in the midst of what could turn out to be glorious Olympic campaigns. And many more are still waiting for their turns to compete.

But those athletes better beware, lest they fall victim to The Curse of the Flag-Bearer.