Lucas caught a 22-yard touchdown pass in the second quarter for Amsterdam (4-1), and finished with three catches for 60 yards. Last week, he had a league-record four touchdown receptions.
Lucas is third in the league in receptions with 17 for 325 yards for a sparkling average of 19.1 yards per catch. He spent most of the season on Green Bay's practice squad last year. He did not have any catches in the two games that he was on Green Bay's 53-man roster.
Quarterback Gibran Hamdan (Seattle) threw for 244 yards and three touchdowns for the Admirals.
Dallas Cowboys-allocated quarterback Drew Henson threw for 187 yards and 2 touchdowns, but he was intercepted by safety Cory Peoples (Philadelphia Eagles) with 1:16 remaining to end any hopes of a late comeback by Rhein (4-1).
Hamdan threw the game-winning touchdown pass to wide receiver Skyler Fulton (Seattle Seahawks) from 42 yards out with just over six minutes remaining in the game.
It took the Admirals just two plays and less than a minute to penetrate the league's toughest defense as Hamdan connected Lucas for a 33-yard gain. He then found Fulton for a 33-yard touchdown strike and a 7-0 lead.
Lucas' Amsterdam teammate, tight end Tory Humphrey, hauled in a 19-yard scoring toss in the third quarter. He finished with three catches for 41 yards.
Packers receiver Vince Butler caught one pass for 15 yards for Amsterdam.
Packers safety Atari Bigby tied for the Admirals' lead with eight tackles and one pass defensed.
Packers cornerback Therrian Fontenot and center Pete Traynor started for Rhein. Fontenot had one tackle, while Rhein's running game struggled to 75 yards on 28 attempts, with a long of 9 yards.
In Frankfurt's 17-13 victory over Hamburg, Packers defensive tackle Jerome Nichols recorded a sack and five tackles.