Storylines to know as track and field returns with indoor worlds

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The world indoor athletics championships may not be the biggest event on the calendar, but it does provide an entry point to what promises to be a fascinating season in track and field. The meet begins on Friday in Serbia with sessions at 3:35 a.m. and 11:55 a.m. ET on CBCSports.ca, CBC Gem and the CBC Sports app. Watch all the action through Sunday here. Canada is sending a team of 12 women and six men — a list highlighted by Olympic decathlon champion Damian Warner but missing fellow medallists Andre De Grasse and Moh Ahmed. Beyond this weekend, the next key event comes when season-long Diamond League action begins in May. The crown jewel of the season arrives in July with the more coveted outdoor world championships, set to take place for the first time ever at the home of Nike in Eugene, Oregon. Because of pandemic-induced schedule changes, it's also the start of back-to-back years featuring world championships for the first time ever. Here are some storylines you should know heading into the season:The men's 100 metres remains a mystery. This was the case before the Tokyo Olympics, where Italian longshot Lamont Marcell Jacobs took the gold medal, immediately faced doping questions and didn't race again until February. Now, things are even more muddled. American Christian Coleman was the pre-Olympic favourite before missing the Games due to a doping-related suspension, but he's back now and set to go head-to-head with Jacobs in the 60m at indoor worlds, where the 100m won't be contested. There's also De Grasse, who won 100m bronze at each of the last two Olympics. The