The caretaker boss clearly stated in his weekly pre-match media conference that he was duty-bound to start the five loan players that Rangers signed from Newcastle on Monday in every match they are fit to play in.
McDowall revealed that former Newcastle managing director Llambias and club chairman Sandy Easdale had issued him with the orders - but the former appeared to deny the claims several hours later.
Burundi-born Gael Bigirimana, English defender Remie Streete, Slovenia midfielder Haris Vuckic, Northern Ireland international Shane Ferguson and Swiss defender Kevin Mbabu have all joined the beleaguered Ibrox club until the end of the campaign.
The first three are in line for their debuts in the William Hill Scottish Cup fifth-round clash with Raith Rovers at Ibrox on Sunday, but the latter two are carrying injuries which will delay their arrivals for several weeks.
Their arrival came amid the backdrop of a power struggle between Newcastle owner Mike Ashley, who has an 8.92 per cent stake in the Scottish Championship club, and other shareholders including Dave King, whose requisition for a general meeting to oust the board must be answered by the club on Friday.
Ashley and the club face hearings before the Scottish Football Association in March over the Sports Direct owner's possible breaches of dual interest rules - and that issue appeared more than pertinent at an extraordinary morning press conference at Murray Park.
McDowall, who took over from Ally McCoist in December when the Gers boss was put on garden leave after announcing his intention to quit, said: "On Monday night I got a call from Derek saying he had secured five players on loan.
"Three of them arrived and two of them will be coming the next three or four weeks, they are injured. When I was given the job I was told players incoming and outgoing wouldn't be my responsibility.
"I take the team and coach the team and I am more than happy to get on with it."
Asked if he was duty bound to play them, he replied: "Yes".
McDowall, who himself is working a 12-month notice period, was then asked if he had to play every one of them every week.
"Yes," he replied. "I have been told what to do and I have told them I am more than happy to carry out what they have told me, so I don't have a problem with it at all.
"They are obviously good players, they play for Newcastle but I will carry on and do what I am told to do."
Quizzed about how the dressing room might be affected by clear interference in team selection, he said: "That's the nature of being at a big club. There are always new players arriving at big clubs and it is something the players will have to deal with.
"The boys have come up to play and they will play. That's just how it is. They are in the squad for Sunday.
"I have handed in my notice and have told the guys I am happy to take the team.
"So I am not going to complain. I will carry out the instructions that they give me and do my best. I have a job to do and I am happy to do it.
"I would like to think the players would be professional and do their jobs.
"And I would like the fans would give them their support, they are playing with Rangers after all.
"The lads are just here to play football. They are nice lads and look good players. It is not their doing. They are a welcome addition to our squad."
Llambias later issued a short statement to Sky Sports News HQ, which read: "There's no way the board is picking the team.
"The basis of any loan deal is that the players who arrive bolster the side and give the squad more depth. That's exactly what is happening here."
Midfielder Fraser Aird soon came into the media room unaware, like the rest of his team-mates at that point, that he could be fighting for only five outfield places for the rest of the season.
"I don't know what it's going to be like," he said. "Ask me in a few weeks and I might tell you something different.
"It's puts him (McDowall) and me in a bit of a position because you know if you've done well enough to play the next week, maybe you won't.
"So I guess you just need to go out and score a hat-trick every game to try to keep yourself in the team."
To complete a bizarre day, Rangers put a story on their official website at 6pm which quoted McDowall as saying there was no certainty that Bigirimana, Vuckic and Streete would play against Raith, with the latter reported to have worked separately with the physio following a "slight injury".
The McDowall quotes read: "All of the new boys are in the squad for Sunday and at the moment it's too early to say if any would be involved in the game. As ever, we'll have a look at the end of the week and see who is fully fit and who is not."