BEIJING (AP) Usain Bolt's coach believes he looks good. So if Glen Mills is happy, Bolt is happy.
And everyone else should be very worried.
The powerful Jamaican returns to the Bird's Nest - the place where he broke three world records while winning three gold medals at the 2008 Beijing Games - to defend his 100-meter title at world championships.
It's a strong field, too, with American teammates Justin Gatlin and Tyson Gay, along with Jamaican sprinter Asafa Powell, sure to push Bolt. The first round begins Saturday and the final is set for the following night.
This has not been a good season for Bolt. He's been hobbled by joint problems that caused him to ''pretty much run slow.'' His most recent time was 9.87 seconds, which is .29 slower than his world record, but was at least a step in the right direction.
Of course, he's the favorite. But Gatlin is listed as a close second-favorite, at around 6-5 by several European sports books. The American hasn't lost in two seasons, but none of his wins have had Bolt in the field.
''I'm ready to go,'' said Bolt, who turned 29 on Friday. ''All I need to do right now is execute.''
Bolt sort of enjoys the what's-wrong-with-Bolt story line. It was something like that at the London Olympics, when he was less than 100 percent and entered the games following losses to teammate Yohan Blake at the Jamaican Olympic trials. Bolt dominated the Olympics and won three more gold medals.
''As soon as I get injured, people start to question if I can come back from injury,'' Bolt said. ''They're writing, `Usain Bolt is injured' or `Usain Bolt won't come back' or ''Usain Bolt will get beat.' I ignore what's going on and put the work in to get it right.''
Bolt had some good training sessions leading up to worlds, with Mills complimenting his protege on his burst out of the blocks, which has long caused the 6-foot-5 sprinter problems.
''Coach was smiling - a thumbs-up to me,'' Bolt said, laughing.
While Bolt has been track's fun-loving champion, Powell (six months), Gay (one year) and Gatlin (four years) have all served doping suspensions. The expected main showdown between Bolt and Gatlin has been portrayed as good vs. evil.
Not that simple, Gatlin insists.
''I've done a lot of great things before that situation,'' said Gatlin, who won the 100 gold at the 2004 Athens Olympics. ''I've done a lot of great things after that situation. I'm more than just four years. I'm more than that.''
Here are some things to know about Day 1 of world championships:
KEEPING PACE: The weather is supposed to be a comfortable 23 degrees Celsius (74 degrees Fahrenheit) when the men hit the streets for the marathon in the morning. A more important number to watch will be the air quality index. On Friday, the reading by the U.S. Embassy Beijing Air Quality Monitor listed it as ''good'' after ranging between ''moderate'' and ''unhealthy for sensitive groups'' in recent days. Stephen Kiprotich of Uganda is the defending champion.
UNDER SCRUTINY: All eyes in the 10,000-meter race will be on Mo Farah and Galen Rupp. Farah, the defending champion, and Rupp, the 2012 Olympic silver medalist, are both coached by Alberto Salazar, who is under investigation by the U.S. Anti-Doping Agency for allegedly encouraging Rupp and other runners to skirt anti-doping rules.
HER SPOTLIGHT: Olympic champion Jessica Ennis-Hill returns to the heptathlon after the birth of her son last year. The British standout made a late decision to compete in the two-day event that starts Saturday. ''I am a different athlete now,'' Ennis-Hill said.
NEW CHAMPION: Valerie Adams of New Zealand won't defend her shot put title after undergoing shoulder and elbow surgeries last September and a minor knee procedure this month. Adams is a four-time world champion and two-time Olympic gold medalist.
RUDISHA'S RETURN: With an opening round 800-meter race, David Rudisha of Kenya takes the first step toward reclaiming his world title. The 2012 Olympic champion missed the worlds two years ago with a bad knee.