Sridarth was the top performer, scoring a brace, while Shubho Paul was also not too far behind, scoring a first-half goal and providing an assist for Taison Singh in the second half.
Qatar enjoyed 63% possession and had 13 shots on target but Gurpreet was unbeatable.
Mandhar broke Indian hearts when he flicked the ball past Gurpreet Singh Sandhu to restore parity in the 82nd minute.
Igor Stimac has acknowledged that Oman, along with Qatar, are the two strong favourites in the group.
The last time the two teams faced off was in a friendly game in December 2018 where the match ended in a goalless draw in Abu Dhabi.
Stimac predicted a tough match on Thursday, considering that India have never won any FIFA-recognised match against Oman.
India begin their campaign against Oman on September 5 in Guwahati followed by an away game against Asian champions Qatar in Doha on September 10.
India, who had lost 2-4 against Tajikistan and 2-5 against North Korea, collected their first points of the tournament though they ended at the bottom of the table with just one point.
The second batch of players released includes Narayan Das, Salam Ranjan Singh, Dhanpal Ganesh, Rowllin Borges, Komal Thatal.
India's football team coach Igor Stimac has warned that players won't be selected on reputation.
As a coach, Stimac's major achievement was guiding Croatia to qualify for the 2014 FIFA World Cup in Brazil.
India and Myanmar got seven points each from three matches but the home team advanced to the third round on the basis of superior goal difference.
Sven-Goran, who was in charge of England for five years until 2006, had last month expressed his interest regarding the job to the All India Football Federation (AIFF).
Bahrain scored the decisive and only goal of the match in the injury time to beat India in a do or die clash.
India secured a stunning 4-1 win over Thailand before going down 0-2 to hosts United Arab Emirates in a group match in which Sunil Chhetri and Co. had more clear chances than their opponents.
A draw against Bahrain, currently ranked 113, will be enough for India (ranked 97) to qualify for the round of 16 for the first time in the continent's showpiece event.
UAE moved top of the table in Group A with four points from two matches while second-placed India still remained in the hunt for a knockout berth with three points from two outings.
The Indian defence played a vital role in keeping the Thai attackers at bay in their last game, and Kotal believes that the back-four has a good chemistry between themselves.
India will play their first match on Sunday against Thailand here, followed by games against UAE (Abu Dhabi) and Bahrain (Sharjah) on January 10 and 14 respectively.