"In Brightest Days Past"
Kyle Raynor is sent through time by Brainiac-5 from the 30th century and finds himself fighting side by side with another Green Lantern! And it is none other than Hal Jordan who is confronted by Sinestro! And not only is Hal alive, but so are the Guardians, the Green Lantern Corps, and the Central Battery is still intact!
Kyle suddenly realizes that he has arrived in the past! When the Guardians find out that Kyle is lost in time, they announce their intent to return him to his time. But Hal argues otherwise, since Kyle's ring gives him the power to counter Sinestro's yellow based ring.
So the duo put together a plan to tackle Sinestro with the help of the Green Lantern Corps.