The top two seeds took their places in the quarter-finals of the Abierto Mexicano de Raquetas in Mexico - but both were tested in the opening round of the new PSA World Tour International 70 event being staged on an all-glass court in the Plaza de los Martires in Toluca.
French favourite Gregory Gaultier (pictured) was stretched for 72 minutes by qualifier Saurav Ghosal - and dropped his first game in five Tour meetings with the Indian number one before coming through 11-1, 11-8, 6-11, 11-9.
"Lost 3-1 tonight...11-9 in the 4th," said Ghosal later on Twitter. "Really disappointed not to take it to the 5th :( good performance but I so wish I won!"
"Really happy to win in 3 against Anjema!" El Shorbagy tweeted later. "Always tough playing him but I am glad that I played really well and couldn't have played better!!"
Second seed Karim Darwish prevailed in straight games - but the world No5 from Egypt was taken to tie-breaks in two of the games before overcoming Botswana's world No12 Alister Walker 11-5, 12-10, 13-11.
But there was Egyptian disappointment elsewhere in the event when four-time world champion Amr Shabana was forced to retire injured midway through his match with Spain's Borja Golan. The No3 seed from Cairo drew level after Golan took the opening game, but the left-hander shook hands with the Spaniard after the third to concede the match.
The Spanish number one will now take on the top-ranked German Simon Rosner. On the day the 24-year-old from Paderborn celebrated a new career-high world No16 ranking, he faced English qualifier Chris Simpson, who was also delighting in a best ever ranking of 37.
Simpson took the opening game and went on to take Rosner the full distance - but the German star ultimately triumphed 11-13, 11-6, 11-8, 8-11, 11-7 after 70 minutes to take his anticipated place in the last eight round.
Both players described the game as 'brutal' - Rosner tweeting "Got through a brutal opener against Chris Simpson 3:2..he played some great Squash-looking forward to tomorrow's match!!"; while Simpson's Twitter report read: "Another brutal 5 setter, unfortunately I was on the wrong end, went down 11/7 in the 5th to world no 16 Simon Roesner tonight."
The younger El Shorbagy brother Marwan El Shorbagy was also in first round action after coming through the qualifiers. The 19-year-old world junior champion took England's fourth seed Peter Barker to five games - but the experienced Londoner ultimately prevailed 11-5, 6-11, 11-6, 6-11, 11-4.
El Shorbagy senior was quick to report on the match on Twitter: "My brother just lost to Peter Barker 3/2!! So happy and proud of him!! Playing such a physical match in the altitude against a top 8 player!"
Marwan himself latter added: "Disappointed to lose 3-2 to Peter Barker but satisfied with my performance! Looking forward to my next tournament next week in Dayton!"
"Won my match against the "flying finn" Olli Tuominen in 5 hard fought games," said Muller on FaceBook. "18/16 first game! Nice to finally win a match again in 5!! Now I can relax and watch the matches on the show court, as there are some massive first round matches...."
 Gregory Gaultier (FRA) bt [Q] Saurav Ghosal (IND) 11-1, 11-8, 6-11, 11-9 (72m)
Mohamed El Shorbagy (EGY) bt Laurens Jan Anjema (NED) 11-8, 11-9, 11-4 (34m)
Nicolas Mueller (SUI) bt [Q] Olli Tuominen (FIN) 18-16, 11-5, 7-11, 13-15, 11-3 (60m)
 Peter Barker (ENG) bt [Q] Marwan El Shorbagy (EGY) 11-5, 6-11, 11-6, 6-11, 11-4 (61m)
Borja Golan (ESP) bt  Amr Shabana (EGY) 11-9, 7-11, 11-9, 6-3 ret. (39m)
Simon Rosner (GER) bt [Q] Chris Simpson (ENG) 11-13, 11-6, 11-8, 8-11, 11-7 (70m)
Omar Mosaad (EGY) bt Alfredo Avila (MEX) 11-9, 11-7, 11-6 (49m)
 Karim Darwish (EGY) bt Alister Walker (BOT) 11-5, 12-10, 13-11 (35m)
 Gregory Gaultier (FRA) v Mohamed El Shorbagy (EGY)
 Peter Barker (ENG) v Nicolas Mueller (SUI)
Borja Golan (ESP) v Simon Rosner (GER)
 Karim Darwish (EGY) v Omar Mosaad (EGY)