Coaching from the sidelines is a no-no in professional tennis.
The theory is players should think through their strategies and problems using their own intelligence and mental strength, on a level-playing field with their opponent.
Tony Abbott is attempting the political equivalent of coaching from the sidelines.
But in this case, the advice has put the player - Malcolm Turnbull - in a bind and, potentially, off his game.
The former prime minister pledged in September that he would make the leadership change to Turnbull as easy as he could.
"There will be no wrecking, no undermining and no sniping. I've never leaked or backgrounded against anyone. And I certainly won't start now," Abbott said at the time.
But that did not rule out giving frank and even critical advice when he feels like it.
Abbott made his first major policy intervention in the coalition party room this week, speaking candidly about the government's budget strategy.
He defended the 2014 budget, which sparked the downward slide of the coalition's political fortunes and the beginning of leadership rumblings.
Abbott told his colleagues the government needed to revisit the task started in 2014 and with Turnbull's impressive communication skills this could be done.
The pep talk from the sidelines is a two-edged sword for Turnbull.
Coach Abbott is saying Turnbull must reach for the sky in finding more budget savings.
But the subtext is if Turnbull and Scott Morrison don't do this, then coalition MPs would be right to question the direction in which they are being led.
The twist is that if Turnbull retains most of Abbott's legacy - in terms of the budget, climate policy, refugees and other key issues - and goes on to win the election it will be a positive for Abbott and his supporters.
Turnbull is seeking to make a positive of this.
In the party room, he responded to Abbott's speech by saying that leadership is about "continuity and change" and that many of the things being done by the Turnbull government were begun under Abbott.
While these sorts of comments will go some way to satisfy the Abbott supporters in the party room, they also feed into Labor's political attack.
"Tony Abbott's cuts are now Malcolm Turnbull's cuts," shadow treasurer Chris Bowen said this week.
Labor frontbencher Andrew Leigh put it more humorously when defending the party's negative gearing policy.
"The prime minister is running a desperate scare campaign which frankly makes him look a whole lot more like Tony Abbott in a silver wig than the economic leader that he promised that he would be," Leigh said.
While the government has been hammering Labor's plan to limit negative gearing to new homes, there are divisions within the coalition over whether to rule out any changes or make minor changes to the concessions given to wealthy Australians.
Ruling out changes would put more steel into the government's attack, but limit the prospects of finding savings to pump into income tax cuts.
Abbott entered the fray in the party room, backing colleagues advocating for negative gearing to be left alone.
He's also likely to give the government grief if it backs one of the only options left if it is to find big savings - winding back high-end superannuation concessions.
As Abbott said last year: "We aren't ever going to increase the taxes on super, we aren't ever going to increase the restrictions on super because super belongs to the people - it's not a piggy bank to be raided by government."
Abbott's interventions have given Labor a wealth of material to work within parliament.
Federal police are now investigating the leak of a confidential cabinet document on the timing of the new submarines, following a news story in which Abbott was critical of what could be a decade or more delay.
Abbott also threw his weight behind criticism of the Safe Schools program by conservative coalition MPs.
And he got in ahead of the defence white paper, putting his view about the need for higher defence spending: "No government can be economically responsible at the expense of national security."
There are echoes of the Kevin Rudd-Julia Gillard saga.
But that was more like a slugfest from the baseline than the long rallies we are seeing between Turnbull and Abbott.
