Former Nottingham Forest and Leicester City midfield man Mills was brought in as Anth Smith’s replacement after the Wearsider resigned following three defeats in the first week of the season.
Rush held the fort and steadied the ship as caretaker-manager but has been replaced as Mills’ number two by former Tottenham and Reading midfielder Darren Caskey.
Caskey will be in the dressing room for the first time today when Gateshead take on Forest Green Rovers in Gloucestershire.
The Tynesiders enter the game on the back of narrow wins over Tamworth and Chester, while Forest Green have lost their last three games and have slipped into the bottom half.
Gateshead have never won at The New Lawn, a 1-1 draw in 2010/11 their best attempt, with the other three west country meetings going the way of the home side, albeit narrowly.
While Mills and Caskey look to get their partnership off to a positive start, Rush hopes the duo can take Gateshead back into the Football League.
“The news that I was no longer wanted came as a bit of a shock, coming as it did after two wins,” said Rush. “But Gary wanted to bring his own man in and I have to respect that decision.
“There are good players at Gateshead and I fully expect the side to push on up the table. It would be great if they could win promotion and if the players stick at it they can achieve a lot.
“It has been a domino effect with Anth Smith going and now myself, but the side has turned the corner and they can go to Forest Green and get something.”
If Gateshead are to achieve that first win at Forest Green they will have to do so without two of their regular midfield men as Josh Walker and Jamie Chandler are both injured.
On the plus side new signing John Oster, the former Sunderland and Everton player, returns to the squad after missing the midweek win over Chester due to the birth of his first child.
Mills may be tempted to start the Wales international despite the 34-year-old playing only half-an-hour in the last six months after leaving Barnet.
“Oster would have started on Tuesday but I got a text to say his wife had gone into labour,” said Mills. “He’s experienced and a quality player, and it’s good to have him available.”