Updated

China and the United States will trade the medal lead back and forth over the course of the 2012 London Olympics. Monday afternoon's swimming events helped the Americans tie China for the lead, but a couple of disappointments prevented the U.S. from taking it outright heading into Tuesday.

Matt Grevers kicked off the U.S. pool party with an Olympic record and an easy gold medal victory in the men's 100m backstroke, thoroughly outclassing the field in the race's second 50 meters. Fortunately for Team USA, though, the silver went to Nick Thorman, making the event the first time in the 2012 Olympics that the U.S. has gotten two medals from one event.

Missy Franklin also made good on being the favorite in the water, pulling away for a win in the women's 100m backstroke for her first Olympic gold medal. She'll have four more chances to add to the Team USA tally.

However, Ryan Lochte, projected to dominate these Olympics by many, surprised in the men's 200m freestyle, finishing fourth and well behind Yannick Agnel, the French star of the pool so far. Agnel has helped France get three medals in the pool, nearly doubling its lifetime total entering 2012.

And the chances of a U.S. double in the women's 100m breaststroke by Rebecca Soni and Breeja Larson were dashed in part by Lithuania's 15-year-old Ruta Meilutyte, who repeated a stunning semifinal performance by taking gold, relegating Soni to silver. Larson finished sixth in the event.

With four medals in the water, though, Team USA erased lead China had (the Chinese won just one swimming medal on Monday, Sun Yang's silver in the men's 200m freestyle), and gave itself another good chance to take the lead on Tuesday. The U.S.'s 12 swimming medals to this point are by far the most any nation has in one sport at the 2012 Olympics, and more than any other nation, save China, has won across all sports.

Team USA also accomplished a significant lifetime goal: Soni's silver was the U.S.'s 500th swimming medal in Olympic history, which only outstrips Australia's second-best tally by 333 medals.

Here's a more complete look at the medal count:

  1. China, 17 (9 gold, 5 silver, 3 bronze)
  2. United States, 17 (5, 7, 5)
  3. Japan, 11 (1, 4, 6)
  4. Italy, 8 (2, 4, 2)
  5. France, 7 (3, 1, 3)

Other notables: The only team beyond that top five with three gold medals is North Korea; Great Britain moved into a five-way tie for ninth with its third medal; mighty Moldova still has one bronze medal.

You can find a more view-friendly medal count right here:

For complete coverage of the 2012 London Olympics, visit SB Nation's Summer Olympics hub.