The Voice coach digitally released her new single 'Your Body' in the US earlier today (September 18), after previewing the accompanying music video last night.
"@therealXtina just bought your new single. Seems the old Christina i loved has returned! Congratulations!! :)" GaGa tweeted.
Aguilera has spoken highly of GaGa in the past, stating that she has the "utmost respect for her" back in 2010.
"She works her ass off, which we all do as women in this business and it just sucks that as women we have to deal with that sort of comparison thing that men don't necessarily," Aguilera said.
Christina Aguilera's new single 'Your Body' is available to download now in the US and will be available internationally in the coming weeks.
Listen to Christina Aguilera's 'Your Body' below: