Derby County have signed midfielders Bradley Johnson and Jacob Butterfield from Norwich City and Huddersfield Town respectively.
Johnson is thought to have joined for a club record fee of around £6m, while Butterfield also moves for an undisclosed fee, that is around £4m.
Butterfield, 25, and Johnson, 28, have both signed four-year contracts.
Head coach Paul Clement said bringing in Johnson was a "major "coup" and his experience will prove "invaluable".
Clement added: "He knows how to get out of this division and is a leader."
Johnson scored 15 goals in 45 appearances for the Canaries as they won promotion to the Premier League last season and featured in all five games so far this term.
Both players will provide cover for Will Hughes, who has been ruled out for six months with a knee injury.
Clement added: "Jacob is a very talented player that is experienced at Championship level."
Butterfield signed for Huddersfield from Middlesbrough in August 2014 as part of a swap deal for Adam Clayton.
The 25-year-old made 52 appearances for the Terriers, scoring seven goals and was their player of the season in 2014-15.
Find all the latest football transfers on our dedicated page.