Instead of a direct fight, the player will face Metal Sonic in a race to the finish across Stardust Speedway. The player must run through Stardust Speedway whilst trying to outrun Metal Sonic. The race course contains many rises and dips as well as spikes, making it hard for the player to maintain speed. During the race, Dr. Robotnik will also follow the racers from behind while bombarding the highway with a high-powered laser emitting from the bottom of his Egg Mobile; if the player falls too far behind, they will get hit by Robotnik's laser, instantly losing a life even if the player has Rings.
At the start of the race, the player will encounter Metal Sonic at a door. Once the door opens, the race will start. Though Sonic is unable to use his Spin Attack against Metal Sonic during the race, Metal Sonic can attack Sonic anytime. While running along normally does not allow the two to interact, Metal has two moves he can utilize depending on the situation: the V. Maximum Overdrive Attack, which is used when the player gains the lead, and the Ring Spark Field, which is used when Metal Sonic is in the lead. The first move allows Metal Sonic to gain a burst of speed that not only destroys any spikes in his pathway but can also harm Sonic, who will stop in his tracks if he gets hit. The second move, though causing Metal to slow down, grants him an electrical field around him that lets him harm Sonic and plow through spikes.
In the player's case, there will be an alternate pathway above Metal Sonic, which not only lets the player run forward without fear of running into Metal Sonic, but with any luck will place them far ahead in the race.
At the end of the race, there is a door not unlike the one at the start. If Metal Sonic wins the race, Metal Sonic will run through the door before it closes, leaving the player stuck on the other side. The player is then hit by Robotnik's laser, losing a life whilst Metal Sonic gloats. If the player wins the race, Sonic will pass through the door before it closes, causing Metal Sonic to crash into the door and fall to his doom, forcing a disgruntled Robotnik to flee. Beyond the door, the player will find a tied-up Amy Rose. The player must free Amy, who will be more than happy to hug Sonic as a sign of affection, in order to finish the boss level.
- In the race, Sonic can actually outrun the V. Maximum Overdrive Attack, though he must use the Super Peel Out to do so.
- In the Japanese and European Mega CD versions of Sonic the Hedgehog CD, the Bad Future music plays during the race even if the player is in the Good Future. This does not happen in the US version. However, in the 2011 remaster, the Bad Future music plays no matter which region's soundtrack the player is using.