Wrist spinners generally get more turn than finger spinners, with left-armer Yadav striking twice in India's 89-run hammering of arch-rivals Pakistan in Manchester on Sunday to prove his worth on English pitches that often favour the quicks at this stage of the season.
Chahal's leg-spinners did the damage in India's first World Cup outing against South Africa, with the bowler returning figures of 4-51.
Calls were made to replace Yadav with paceman Mohammed Shami against Pakistan but former India off-spinner Harbhajan said the team should stick with the spin twins.
"It is a very good combination," Harbhajan told AFP. "The results that India have got in the last two-and-a-half years, a lot of credit should be given to these guys.
"I would like to see them playing together, because none of the other teams have got two spinners and they don't have the habit of playing spin in the middle overs.
"It has worked for India to play two spinners, even in English conditions, because they are wrist spinners. If India are thinking about their best XI then these two will feature in all the games."
The two bowlers have 168 one-day international wickets between them in the three years since Chahal made his international debut in 2016. Yadav played his first ODI the following year.
The 24-year-old Yadav is 10 away from a century of wickets with an impressive economy rate of 4.92 in 47 ODIs.
"He has definitely got the capabilities and the talent to be there for a long period of time," said the 38-year-old Harbhajan, who last played for India in a 2016 Twenty20 match.
"(India coach) Ravi Shastri said he is our number one bowler. So it's good that the team is backing him," said Harbhajan, one of India's finest off-spinners, who took 417 wickets in 103 Tests and 269 wickets in 236 ODIs.
India, second in the ODI rankings, have been hit by injuries to opening batsman Shikhar Dhawan - out of the rest of the World Cup - and paceman Bhuvneshwar Kumar.
But Harbhajan said Virat Kohli's side have strength in depth with Shami, who is yet to play at the World Cup, likely to replace Kumar in the next match against Afghanistan on Saturday.
"I think Shami is capable enough to win games on his own. He is one of those guys who has been a matchwinner on his own," said Harbhajan.
Harbhajan credited Kohli for a fitness revolution that has improved all aspects of India's game, particularly their fielding.
"They are fit, agile, a proper fielding squad. All the credit must be given to Kohli for changing the face of Indian cricket in terms of fitness," said Harbhajan, a member of the 2011 World Cup-winning team.
"So if you have better fitness then your results always follow the way you want them to be."
Harbhajan said England, holders Australia, New Zealand and India - the current top four - would qualify for the semi-finals, with Kohli's side the team to beat in the knockout phase.
"To beat India they (other teams) will have to bring their 'A' game on that day. India will be a very tough side to beat," he said with a smile.