Leinster are five points clear at the top of Conference B after the defending champions beat Munster at the Aviva Stadium.
Leinster's Pro14 title defence continued with a fourth win in five, with Glasgow Warriors and the Ospreys matching that return on Saturday.
The Cheetahs' three-match losing run in Pro14 ended but a last-gasp try saw Ulster deny them victory.
Edinburgh saw off Connacht to record their first Pro 14 win as Munster thrashed a much-changed Ospreys side on Friday.
John Cooney kicked a last-gasp penalty for the second successive week as Ulster left it late to beat Pro14 rivals Edinburgh.
John Cooney's kicking got Ulster up and running, while Connacht's Craig Ronaldson fell just short and Munster ran riot in Pro14.
Peter Stringer played 98 times for Ireland and won the Grand Slam during his distinguished 11-year international career.
Rory Best's hamstring injury means he will miss Ireland's three-match series in Australia next month.
Munster came within striking distance of upsetting European champions Leinster, but the hosts hung on to reach the Pro14 final.
The Pro14 semi-final line-up is complete, with Scarlets to play Glasgow Warriors, while Munster take on Leinster.
Racing 92 were superb for much of their semi-final against Munster, but Laurent Labit says they will have to be even better in the...
Read more
There will be no all-Irish European Champions Cup final in Bilbao after Racing 92 dominated the first half in a defeat of Munster.
Johan Goosen's return to rugby was spoiled by Munster, who engineered an impressive second-half turnaround at the Cheetahs in Pro14.
Scarlets picked up an impressive win over Glasgow Warriors to keep the pressure on Leinster, while Benetton, Cheetahs and Munster also won.
An absorbing Champions Cup quarter-final between Munster and Toulon was won by the former thanks to a superb solo try from Andrew Conway.
Leinster suffered a surprise Pro14 defeat against Ospreys on Saturday, while Cardiff Blues won for a fifth game in a row.