Rossi was the established team leader when Lorenzo arrived at Yamaha in 2008, and after two strong seasons by the Spaniard, the Italian expressed his belief that giving both riders equal status was an unsustainable situation.
The pair's animosity manifested itself in the construction of a wall dividing either side of the garage in 2010. Lorenzo won his first world crown that year, with Rossi departing to Ducati.
Now established as Yamaha's leader, Lorenzo has welcomed Rossi's return while the Italian insists he will start the year as the number two rider.
Masao Furusawa, the guiding hand behind Yamaha's YZR-M1 project, recently warned the situation could once more become unmanageable, but Lorenzo refutes that fear.
"Probably too much was made of the wall, for the importance it had," Lorenzo said.
"This is a very individual sport, [because] everyone is interested in his own job. It's not like playing football or basketball.
"Anyway it doesn't matter - no wall this time."
Rossi, who tested for Yamaha in November, said his first days at the Japanese team felt like he had "never been away."