Jermaine McGlashan scored in stoppage-time to rescue a point for Cheltenham and deny Portsmouth their first away win of the season.
Patrick Agyemang had given Portsmouth the lead from close range, in their first competitive game with the Robins, after a stumble by Steve Elliott.
McGlashan levelled from Terry Gornell's pass but Johnny Ertl restored Pompey's lead from a cross by Jed Wallace.
McGlashan beat keeper John Sullivan to the ball to grab the late equaliser.
VIEWS FROM THE DRESSING ROOM
Cheltenham Town manager Mark Yates told BBC Radio Gloucestershire:
"We've got to cut out individual and defensive mistakes. We're making bad decisions that are costing us goals and that's everybody.
"Jermaine did some really great things but like all of our players, he's not on top of his game. Even though he scored two goals, he's got to do things better.
"I've told them well done for showing some spirit and just go and think about your performance as an individual and as a team."
Portsmouth manager Guy Whittingham told BBC Radio Solent:
"I'd like to think our first-half performance was decent enough. Second half it was backs to the wall; we didn't keep the ball well enough, didn't move the ball well enough and ultimately all the pressure put on us cost us.
"The first half we created a number of chances, good chances again, and even second half we started brightly and then there seems to be something at the moment where we don't keep playing the football that we're capable of doing, so that we've got to look at.
"Look at the games we've conceded - Mansfield and here - of late. We've defended really well and coped with everything and Sullivan hasn't had much to do.
"It is frustrating, of course it is, but you know it's a good bunch of guys and we know we'll get this right."
Sorry, we were unable to load match stats, please try again.
Live Text Commentary
Full Time The final whistle goes and the game is over.90:00 +6:50
Free kick taken by John Sullivan.90:00 +6:41
Terry Gornell is flagged offside by the assistant referee.90:00 +6:06
Free kick crossed by Matt Richards.90:00 +5:56
Free kick awarded for an unfair challenge on Zack Kotwica by Romain Padovani.90:00 +5:09
Yassin Moutaouakil manages to make a clearance.90:00 +4:58
Matt Richards takes the free kick.90:00 +4:37 Booking
The referee shows Danny East a yellow card for unsporting behaviour.90:00 +4:25
Danny East concedes a free kick for a foul on Jermaine McGlashan.90:00 +1:31 Goal scored
Goal! - Jermaine McGlashan - Cheltenham 2 - 2 Portsmouth Jermaine McGlashan scores with their right foot. Cheltenham 2-2 Portsmouth.90:00 +1:05
Matt Richards takes the free kick.90:00 +0:22
Foul by Sonny Bradley on Byron Harrison, free kick awarded.86:51
John Sullivan takes the free kick.86:42
Russell Penn is caught offside.85:50
Free kick taken by Keith Lowe.85:47
The official flags Romain Padovani offside.84:24
Header at goal by Zack Kotwica misses left of the target.84:15
A cross is delivered by Sido Jombati.79:00 Substitution
Substitution Romain Padovani on for Patrick Agyemang.
Substitution Ryan Bird on for Ricky Holmes.77:05 Substitution
Substitution (Portsmouth) makes a substitution, with Shaun Cooper coming on for Andy Barcham.76:29
Clearance by Johnny Ertl.76:23
Corner taken by Matt Richards.74:38
The ball is swung over by Ricky Holmes.65:11 Substitution
Substitution Byron Harrison comes on in place of Sam Deering.63:43
Corner taken by Sido Jombati from the right by-line.62:48
Andy Barcham takes a shot and cleared the bar.62:21
Free kick taken by Sonny Bradley.62:04
Russell Penn gives away a free kick for an unfair challenge on Simon Ferry.60:14
John Sullivan takes the free kick.59:30
The assistant referee flags for offside against Jermaine McGlashan.57:15
Clearance made by Johnny Ertl.56:50
Free kick crossed by Matt Richards.56:39
Danny East challenges Jermaine McGlashan unfairly and gives away a free kick.56:16 Substitution
Substitution Zack Kotwica comes on in place of Steven Gillespie.54:22
Corner taken by Andy Barcham.53:32
Corner taken by Ricky Holmes from the left by-line.52:58
Danny East restarts play with the free kick.52:51
Sido Jombati concedes a free kick for a foul on Andy Barcham.49:38
Shot by Andy Barcham went over.49:26
Ricky Holmes restarts play with the free kick.48:27
Foul by Russell Penn on Johnny Ertl, free kick awarded.45:01
The referee gets the second half started.45:00 +2:31 Half time
Half Time The half-time whistle blows.45:00 +0:48
Sam Deering restarts play with the free kick.45:00 +0:39
Yassin Moutaouakil concedes a free kick for a foul on Sam Deering.44:53
Shot by Johnny Ertl missed to the left of the target.43:20
Assist by Jed Wallace.43:20 Goal scored
Goal! - Johnny Ertl - Cheltenham 1 - 2 Portsmouth Johnny Ertl scores a right footed goal. Cheltenham 1-2 Portsmouth.40:15
Terry Gornell takes a shot. John Sullivan blocks the ball.38:19
Shot by Jermaine McGlashan cleared the bar.38:07
Corner from the right by-line taken by Sam Deering.35:53
Russell Penn provided the assist for the goal.35:53 Goal scored
Goal! - Jermaine McGlashan - Cheltenham 1 - 1 Portsmouth Jermaine McGlashan scores with their right foot. Cheltenham 1-1 Portsmouth.34:00
Clearance by Johnny Ertl.33:52
Corner taken by Matt Richards from the left by-line.31:54 Substitution
Substitution Russell Penn on for Ryan Inniss.28:06
John Sullivan takes the free kick.27:52
The referee blows for offside.27:05
The ball is delivered by Sido Jombati.24:38
Corner taken by Ricky Holmes from the left by-line.23:31
John Sullivan takes the free kick.23:16
Jermaine McGlashan challenges Danny East unfairly and gives away a free kick.20:13
Clearance by Keith Lowe.19:58
Corner taken by Ricky Holmes from the left by-line.18:35
Direct effort from the free kick comes in from David Noble and goes over.17:47
Foul by Sonny Bradley on Steven Gillespie, free kick awarded.17:38
Scott Brown takes the free kick.17:26
The referee blows for offside.16:19
Scott Brown restarts play with the free kick.15:12
Patrick Agyemang challenges Keith Lowe unfairly and gives away a free kick.12:27
Patrick Agyemang takes the chance to get an effort at goal and missed to the right of the net.12:14
Yassin Moutaouakil crosses the ball.10:15
Ricky Holmes sends in a cross.6:49
Corner from the right by-line taken by Ricky Holmes.6:28
Free kick taken by Ricky Holmes.5:49
Matt Richards challenges Patrick Agyemang unfairly and gives away a free kick.4:19 Goal scored
Goal! - Patrick Agyemang - Cheltenham 0 - 1 Portsmouth Patrick Agyemang scores with a right foot finish. Cheltenham 0-1 Portsmouth.2:17
Andy Barcham takes a shot and cleared the crossbar.0:00
The referee gets the match started.
Live data and text provided by our data suppliers